diff --git a/.idea/caches/build_file_checksums.ser b/.idea/caches/build_file_checksums.ser
new file mode 100644
index 0000000..9702d48
Binary files /dev/null and b/.idea/caches/build_file_checksums.ser differ
diff --git a/.idea/codeStyles/Project.xml b/.idea/codeStyles/Project.xml
new file mode 100644
index 0000000..30aa626
--- /dev/null
+++ b/.idea/codeStyles/Project.xml
@@ -0,0 +1,29 @@
+<component name="ProjectCodeStyleConfiguration">
+  <code_scheme name="Project" version="173">
+    <Objective-C-extensions>
+      <file>
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Import" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Macro" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Typedef" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Enum" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Constant" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Global" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Struct" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="FunctionPredecl" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Function" />
+      </file>
+      <class>
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Property" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Synthesize" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="InitMethod" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="StaticMethod" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="InstanceMethod" />
+        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="DeallocMethod" />
+      </class>
+      <extensions>
+        <pair source="cpp" header="h" fileNamingConvention="NONE" />
+        <pair source="c" header="h" fileNamingConvention="NONE" />
+      </extensions>
+    </Objective-C-extensions>
+  </code_scheme>
+</component>
\ No newline at end of file
diff --git a/.idea/gradle.xml b/.idea/gradle.xml
new file mode 100644
index 0000000..7ac24c7
--- /dev/null
+++ b/.idea/gradle.xml
@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="GradleSettings">
+    <option name="linkedExternalProjectsSettings">
+      <GradleProjectSettings>
+        <option name="distributionType" value="DEFAULT_WRAPPED" />
+        <option name="externalProjectPath" value="$PROJECT_DIR$" />
+        <option name="modules">
+          <set>
+            <option value="$PROJECT_DIR$" />
+            <option value="$PROJECT_DIR$/app" />
+          </set>
+        </option>
+        <option name="resolveModulePerSourceSet" value="false" />
+      </GradleProjectSettings>
+    </option>
+  </component>
+</project>
\ No newline at end of file
diff --git a/.idea/misc.xml b/.idea/misc.xml
new file mode 100644
index 0000000..99202cc
--- /dev/null
+++ b/.idea/misc.xml
@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="NullableNotNullManager">
+    <option name="myDefaultNullable" value="android.support.annotation.Nullable" />
+    <option name="myDefaultNotNull" value="android.support.annotation.NonNull" />
+    <option name="myNullables">
+      <value>
+        <list size="5">
+          <item index="0" class="java.lang.String" itemvalue="org.jetbrains.annotations.Nullable" />
+          <item index="1" class="java.lang.String" itemvalue="javax.annotation.Nullable" />
+          <item index="2" class="java.lang.String" itemvalue="javax.annotation.CheckForNull" />
+          <item index="3" class="java.lang.String" itemvalue="edu.umd.cs.findbugs.annotations.Nullable" />
+          <item index="4" class="java.lang.String" itemvalue="android.support.annotation.Nullable" />
+        </list>
+      </value>
+    </option>
+    <option name="myNotNulls">
+      <value>
+        <list size="4">
+          <item index="0" class="java.lang.String" itemvalue="org.jetbrains.annotations.NotNull" />
+          <item index="1" class="java.lang.String" itemvalue="javax.annotation.Nonnull" />
+          <item index="2" class="java.lang.String" itemvalue="edu.umd.cs.findbugs.annotations.NonNull" />
+          <item index="3" class="java.lang.String" itemvalue="android.support.annotation.NonNull" />
+        </list>
+      </value>
+    </option>
+  </component>
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_1_7" project-jdk-name="1.8" project-jdk-type="JavaSDK">
+    <output url="file://$PROJECT_DIR$/build/classes" />
+  </component>
+  <component name="ProjectType">
+    <option name="id" value="Android" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/.idea/modules.xml b/.idea/modules.xml
new file mode 100644
index 0000000..5244278
--- /dev/null
+++ b/.idea/modules.xml
@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectModuleManager">
+    <modules>
+      <module fileurl="file://$PROJECT_DIR$/android-persistence.iml" filepath="$PROJECT_DIR$/android-persistence.iml" />
+      <module fileurl="file://$PROJECT_DIR$/app/app.iml" filepath="$PROJECT_DIR$/app/app.iml" />
+    </modules>
+  </component>
+</project>
\ No newline at end of file
diff --git a/.idea/runConfigurations.xml b/.idea/runConfigurations.xml
new file mode 100644
index 0000000..7f68460
--- /dev/null
+++ b/.idea/runConfigurations.xml
@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="RunConfigurationProducerService">
+    <option name="ignoredProducers">
+      <set>
+        <option value="org.jetbrains.plugins.gradle.execution.test.runner.AllInPackageGradleConfigurationProducer" />
+        <option value="org.jetbrains.plugins.gradle.execution.test.runner.TestClassGradleConfigurationProducer" />
+        <option value="org.jetbrains.plugins.gradle.execution.test.runner.TestMethodGradleConfigurationProducer" />
+      </set>
+    </option>
+  </component>
+</project>
\ No newline at end of file
diff --git a/.idea/runConfigurations/Step_1___Dao.xml b/.idea/runConfigurations/Step_1___Dao.xml
deleted file mode 100644
index bd680d9..0000000
--- a/.idea/runConfigurations/Step_1___Dao.xml
+++ /dev/null
@@ -1,51 +0,0 @@
-<component name="ProjectRunConfigurationManager">
-  <configuration default="false" name="Step 1 - Dao" type="AndroidRunConfigurationType" factoryName="Android App" activateToolWindowBeforeRun="false">
-    <module name="app" />
-    <option name="DEPLOY" value="true" />
-    <option name="ARTIFACT_NAME" value="" />
-    <option name="PM_INSTALL_OPTIONS" value="" />
-    <option name="ACTIVITY_EXTRA_FLAGS" value="" />
-    <option name="MODE" value="specific_activity" />
-    <option name="CLEAR_LOGCAT" value="false" />
-    <option name="SHOW_LOGCAT_AUTOMATICALLY" value="false" />
-    <option name="SKIP_NOOP_APK_INSTALLATIONS" value="true" />
-    <option name="FORCE_STOP_RUNNING_APP" value="true" />
-    <option name="TARGET_SELECTION_MODE" value="SHOW_DIALOG" />
-    <option name="USE_LAST_SELECTED_DEVICE" value="true" />
-    <option name="PREFERRED_AVD" value="" />
-    <option name="SELECTED_CLOUD_MATRIX_CONFIGURATION_ID" value="-1" />
-    <option name="SELECTED_CLOUD_MATRIX_PROJECT_ID" value="" />
-    <option name="DEBUGGER_TYPE" value="Auto" />
-    <Auto>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Auto>
-    <Hybrid>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Hybrid>
-    <Java />
-    <Native>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Native>
-    <Profilers>
-      <option name="ADVANCED_PROFILING_ENABLED" value="false" />
-    </Profilers>
-    <option name="DEEP_LINK" value="" />
-    <option name="ACTIVITY_CLASS" value="com.example.android.persistence.codelab.step1.UsersActivity" />
-    <method>
-      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-      <option name="com.android.instantApps.provision.BeforeRunTask" enabled="true" clearCache="false" clearProvisionedDevices="false" myTimestamp="1510919282160" />
-    </method>
-  </configuration>
-</component>
\ No newline at end of file
diff --git a/.idea/runConfigurations/Step_1___Solution.xml b/.idea/runConfigurations/Step_1___Solution.xml
deleted file mode 100644
index 9ea1d6d..0000000
--- a/.idea/runConfigurations/Step_1___Solution.xml
+++ /dev/null
@@ -1,51 +0,0 @@
-<component name="ProjectRunConfigurationManager">
-  <configuration default="false" name="Step 1 - Solution" type="AndroidRunConfigurationType" factoryName="Android App" activateToolWindowBeforeRun="false">
-    <module name="app" />
-    <option name="DEPLOY" value="true" />
-    <option name="ARTIFACT_NAME" value="" />
-    <option name="PM_INSTALL_OPTIONS" value="" />
-    <option name="ACTIVITY_EXTRA_FLAGS" value="" />
-    <option name="MODE" value="specific_activity" />
-    <option name="CLEAR_LOGCAT" value="false" />
-    <option name="SHOW_LOGCAT_AUTOMATICALLY" value="false" />
-    <option name="SKIP_NOOP_APK_INSTALLATIONS" value="true" />
-    <option name="FORCE_STOP_RUNNING_APP" value="true" />
-    <option name="TARGET_SELECTION_MODE" value="SHOW_DIALOG" />
-    <option name="USE_LAST_SELECTED_DEVICE" value="true" />
-    <option name="PREFERRED_AVD" value="" />
-    <option name="SELECTED_CLOUD_MATRIX_CONFIGURATION_ID" value="-1" />
-    <option name="SELECTED_CLOUD_MATRIX_PROJECT_ID" value="" />
-    <option name="DEBUGGER_TYPE" value="Auto" />
-    <Auto>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Auto>
-    <Hybrid>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Hybrid>
-    <Java />
-    <Native>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Native>
-    <Profilers>
-      <option name="ADVANCED_PROFILING_ENABLED" value="false" />
-    </Profilers>
-    <option name="DEEP_LINK" value="" />
-    <option name="ACTIVITY_CLASS" value="com.example.android.persistence.codelab.step1_solution.UsersActivity" />
-    <method>
-      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-      <option name="com.android.instantApps.provision.BeforeRunTask" enabled="true" clearCache="false" clearProvisionedDevices="false" myTimestamp="1510919282160" />
-    </method>
-  </configuration>
-</component>
\ No newline at end of file
diff --git a/.idea/runConfigurations/Step_2___Relationships.xml b/.idea/runConfigurations/Step_2___Relationships.xml
deleted file mode 100644
index 6c22f64..0000000
--- a/.idea/runConfigurations/Step_2___Relationships.xml
+++ /dev/null
@@ -1,51 +0,0 @@
-<component name="ProjectRunConfigurationManager">
-  <configuration default="false" name="Step 2 - Relationships" type="AndroidRunConfigurationType" factoryName="Android App" activateToolWindowBeforeRun="false">
-    <module name="app" />
-    <option name="DEPLOY" value="true" />
-    <option name="ARTIFACT_NAME" value="" />
-    <option name="PM_INSTALL_OPTIONS" value="" />
-    <option name="ACTIVITY_EXTRA_FLAGS" value="" />
-    <option name="MODE" value="specific_activity" />
-    <option name="CLEAR_LOGCAT" value="false" />
-    <option name="SHOW_LOGCAT_AUTOMATICALLY" value="false" />
-    <option name="SKIP_NOOP_APK_INSTALLATIONS" value="true" />
-    <option name="FORCE_STOP_RUNNING_APP" value="true" />
-    <option name="TARGET_SELECTION_MODE" value="SHOW_DIALOG" />
-    <option name="USE_LAST_SELECTED_DEVICE" value="true" />
-    <option name="PREFERRED_AVD" value="" />
-    <option name="SELECTED_CLOUD_MATRIX_CONFIGURATION_ID" value="-1" />
-    <option name="SELECTED_CLOUD_MATRIX_PROJECT_ID" value="" />
-    <option name="DEBUGGER_TYPE" value="Auto" />
-    <Auto>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Auto>
-    <Hybrid>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Hybrid>
-    <Java />
-    <Native>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Native>
-    <Profilers>
-      <option name="ADVANCED_PROFILING_ENABLED" value="false" />
-    </Profilers>
-    <option name="DEEP_LINK" value="" />
-    <option name="ACTIVITY_CLASS" value="com.example.android.persistence.codelab.step2.JankShowUserActivity" />
-    <method>
-      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-      <option name="com.android.instantApps.provision.BeforeRunTask" enabled="true" clearCache="false" clearProvisionedDevices="false" myTimestamp="1510919282160" />
-    </method>
-  </configuration>
-</component>
\ No newline at end of file
diff --git a/.idea/runConfigurations/Step_3___Async_calls.xml b/.idea/runConfigurations/Step_3___Async_calls.xml
deleted file mode 100644
index cefcc50..0000000
--- a/.idea/runConfigurations/Step_3___Async_calls.xml
+++ /dev/null
@@ -1,51 +0,0 @@
-<component name="ProjectRunConfigurationManager">
-  <configuration default="false" name="Step 3 - Async calls" type="AndroidRunConfigurationType" factoryName="Android App" activateToolWindowBeforeRun="false">
-    <module name="app" />
-    <option name="DEPLOY" value="true" />
-    <option name="ARTIFACT_NAME" value="" />
-    <option name="PM_INSTALL_OPTIONS" value="" />
-    <option name="ACTIVITY_EXTRA_FLAGS" value="" />
-    <option name="MODE" value="specific_activity" />
-    <option name="CLEAR_LOGCAT" value="false" />
-    <option name="SHOW_LOGCAT_AUTOMATICALLY" value="false" />
-    <option name="SKIP_NOOP_APK_INSTALLATIONS" value="true" />
-    <option name="FORCE_STOP_RUNNING_APP" value="true" />
-    <option name="TARGET_SELECTION_MODE" value="SHOW_DIALOG" />
-    <option name="USE_LAST_SELECTED_DEVICE" value="true" />
-    <option name="PREFERRED_AVD" value="" />
-    <option name="SELECTED_CLOUD_MATRIX_CONFIGURATION_ID" value="-1" />
-    <option name="SELECTED_CLOUD_MATRIX_PROJECT_ID" value="" />
-    <option name="DEBUGGER_TYPE" value="Auto" />
-    <Auto>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Auto>
-    <Hybrid>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Hybrid>
-    <Java />
-    <Native>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Native>
-    <Profilers>
-      <option name="ADVANCED_PROFILING_ENABLED" value="false" />
-    </Profilers>
-    <option name="DEEP_LINK" value="" />
-    <option name="ACTIVITY_CLASS" value="com.example.android.persistence.codelab.step3.BooksBorrowedByUserActivity" />
-    <method>
-      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-      <option name="com.android.instantApps.provision.BeforeRunTask" enabled="true" clearCache="false" clearProvisionedDevices="false" myTimestamp="1510919282160" />
-    </method>
-  </configuration>
-</component>
\ No newline at end of file
diff --git a/.idea/runConfigurations/Step_3___Solution.xml b/.idea/runConfigurations/Step_3___Solution.xml
deleted file mode 100644
index cbec36e..0000000
--- a/.idea/runConfigurations/Step_3___Solution.xml
+++ /dev/null
@@ -1,51 +0,0 @@
-<component name="ProjectRunConfigurationManager">
-  <configuration default="false" name="Step 3 - Solution" type="AndroidRunConfigurationType" factoryName="Android App" activateToolWindowBeforeRun="false">
-    <module name="app" />
-    <option name="DEPLOY" value="true" />
-    <option name="ARTIFACT_NAME" value="" />
-    <option name="PM_INSTALL_OPTIONS" value="" />
-    <option name="ACTIVITY_EXTRA_FLAGS" value="" />
-    <option name="MODE" value="specific_activity" />
-    <option name="CLEAR_LOGCAT" value="false" />
-    <option name="SHOW_LOGCAT_AUTOMATICALLY" value="false" />
-    <option name="SKIP_NOOP_APK_INSTALLATIONS" value="true" />
-    <option name="FORCE_STOP_RUNNING_APP" value="true" />
-    <option name="TARGET_SELECTION_MODE" value="SHOW_DIALOG" />
-    <option name="USE_LAST_SELECTED_DEVICE" value="true" />
-    <option name="PREFERRED_AVD" value="" />
-    <option name="SELECTED_CLOUD_MATRIX_CONFIGURATION_ID" value="-1" />
-    <option name="SELECTED_CLOUD_MATRIX_PROJECT_ID" value="" />
-    <option name="DEBUGGER_TYPE" value="Auto" />
-    <Auto>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Auto>
-    <Hybrid>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Hybrid>
-    <Java />
-    <Native>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Native>
-    <Profilers>
-      <option name="ADVANCED_PROFILING_ENABLED" value="false" />
-    </Profilers>
-    <option name="DEEP_LINK" value="" />
-    <option name="ACTIVITY_CLASS" value="com.example.android.persistence.codelab.step3_solution.BooksBorrowedByUserActivity" />
-    <method>
-      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-      <option name="com.android.instantApps.provision.BeforeRunTask" enabled="true" clearCache="false" clearProvisionedDevices="false" myTimestamp="1510919282160" />
-    </method>
-  </configuration>
-</component>
\ No newline at end of file
diff --git a/.idea/runConfigurations/Step_4___Solution.xml b/.idea/runConfigurations/Step_4___Solution.xml
deleted file mode 100644
index 5190a18..0000000
--- a/.idea/runConfigurations/Step_4___Solution.xml
+++ /dev/null
@@ -1,51 +0,0 @@
-<component name="ProjectRunConfigurationManager">
-  <configuration default="false" name="Step 4 - Solution" type="AndroidRunConfigurationType" factoryName="Android App" activateToolWindowBeforeRun="false">
-    <module name="app" />
-    <option name="DEPLOY" value="true" />
-    <option name="ARTIFACT_NAME" value="" />
-    <option name="PM_INSTALL_OPTIONS" value="" />
-    <option name="ACTIVITY_EXTRA_FLAGS" value="" />
-    <option name="MODE" value="specific_activity" />
-    <option name="CLEAR_LOGCAT" value="false" />
-    <option name="SHOW_LOGCAT_AUTOMATICALLY" value="false" />
-    <option name="SKIP_NOOP_APK_INSTALLATIONS" value="true" />
-    <option name="FORCE_STOP_RUNNING_APP" value="true" />
-    <option name="TARGET_SELECTION_MODE" value="SHOW_DIALOG" />
-    <option name="USE_LAST_SELECTED_DEVICE" value="true" />
-    <option name="PREFERRED_AVD" value="" />
-    <option name="SELECTED_CLOUD_MATRIX_CONFIGURATION_ID" value="-1" />
-    <option name="SELECTED_CLOUD_MATRIX_PROJECT_ID" value="" />
-    <option name="DEBUGGER_TYPE" value="Auto" />
-    <Auto>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Auto>
-    <Hybrid>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Hybrid>
-    <Java />
-    <Native>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Native>
-    <Profilers>
-      <option name="ADVANCED_PROFILING_ENABLED" value="false" />
-    </Profilers>
-    <option name="DEEP_LINK" value="" />
-    <option name="ACTIVITY_CLASS" value="com.example.android.persistence.codelab.step4_solution.TypeConvertersActivity" />
-    <method>
-      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-      <option name="com.android.instantApps.provision.BeforeRunTask" enabled="true" clearCache="false" clearProvisionedDevices="false" myTimestamp="1510919282160" />
-    </method>
-  </configuration>
-</component>
\ No newline at end of file
diff --git a/.idea/runConfigurations/Step_4___Type_converters.xml b/.idea/runConfigurations/Step_4___Type_converters.xml
deleted file mode 100644
index b186340..0000000
--- a/.idea/runConfigurations/Step_4___Type_converters.xml
+++ /dev/null
@@ -1,51 +0,0 @@
-<component name="ProjectRunConfigurationManager">
-  <configuration default="false" name="Step 4 - Type converters" type="AndroidRunConfigurationType" factoryName="Android App" activateToolWindowBeforeRun="false">
-    <module name="app" />
-    <option name="DEPLOY" value="true" />
-    <option name="ARTIFACT_NAME" value="" />
-    <option name="PM_INSTALL_OPTIONS" value="" />
-    <option name="ACTIVITY_EXTRA_FLAGS" value="" />
-    <option name="MODE" value="specific_activity" />
-    <option name="CLEAR_LOGCAT" value="false" />
-    <option name="SHOW_LOGCAT_AUTOMATICALLY" value="false" />
-    <option name="SKIP_NOOP_APK_INSTALLATIONS" value="true" />
-    <option name="FORCE_STOP_RUNNING_APP" value="true" />
-    <option name="TARGET_SELECTION_MODE" value="SHOW_DIALOG" />
-    <option name="USE_LAST_SELECTED_DEVICE" value="true" />
-    <option name="PREFERRED_AVD" value="" />
-    <option name="SELECTED_CLOUD_MATRIX_CONFIGURATION_ID" value="-1" />
-    <option name="SELECTED_CLOUD_MATRIX_PROJECT_ID" value="" />
-    <option name="DEBUGGER_TYPE" value="Auto" />
-    <Auto>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Auto>
-    <Hybrid>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Hybrid>
-    <Java />
-    <Native>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Native>
-    <Profilers>
-      <option name="ADVANCED_PROFILING_ENABLED" value="false" />
-    </Profilers>
-    <option name="DEEP_LINK" value="" />
-    <option name="ACTIVITY_CLASS" value="com.example.android.persistence.codelab.step4.TypeConvertersActivity" />
-    <method>
-      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-      <option name="com.android.instantApps.provision.BeforeRunTask" enabled="true" clearCache="false" clearProvisionedDevices="false" myTimestamp="1510919282160" />
-    </method>
-  </configuration>
-</component>
\ No newline at end of file
diff --git a/.idea/runConfigurations/Step_5___Custom_Results.xml b/.idea/runConfigurations/Step_5___Custom_Results.xml
deleted file mode 100644
index 7ad9073..0000000
--- a/.idea/runConfigurations/Step_5___Custom_Results.xml
+++ /dev/null
@@ -1,51 +0,0 @@
-<component name="ProjectRunConfigurationManager">
-  <configuration default="false" name="Step 5 - Custom Results" type="AndroidRunConfigurationType" factoryName="Android App" activateToolWindowBeforeRun="false">
-    <module name="app" />
-    <option name="DEPLOY" value="true" />
-    <option name="ARTIFACT_NAME" value="" />
-    <option name="PM_INSTALL_OPTIONS" value="" />
-    <option name="ACTIVITY_EXTRA_FLAGS" value="" />
-    <option name="MODE" value="specific_activity" />
-    <option name="CLEAR_LOGCAT" value="false" />
-    <option name="SHOW_LOGCAT_AUTOMATICALLY" value="false" />
-    <option name="SKIP_NOOP_APK_INSTALLATIONS" value="true" />
-    <option name="FORCE_STOP_RUNNING_APP" value="true" />
-    <option name="TARGET_SELECTION_MODE" value="SHOW_DIALOG" />
-    <option name="USE_LAST_SELECTED_DEVICE" value="true" />
-    <option name="PREFERRED_AVD" value="" />
-    <option name="SELECTED_CLOUD_MATRIX_CONFIGURATION_ID" value="-1" />
-    <option name="SELECTED_CLOUD_MATRIX_PROJECT_ID" value="" />
-    <option name="DEBUGGER_TYPE" value="Auto" />
-    <Auto>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Auto>
-    <Hybrid>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Hybrid>
-    <Java />
-    <Native>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Native>
-    <Profilers>
-      <option name="ADVANCED_PROFILING_ENABLED" value="false" />
-    </Profilers>
-    <option name="DEEP_LINK" value="" />
-    <option name="ACTIVITY_CLASS" value="com.example.android.persistence.codelab.step5.CustomResultActivity" />
-    <method>
-      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-      <option name="com.android.instantApps.provision.BeforeRunTask" enabled="true" clearCache="false" clearProvisionedDevices="false" myTimestamp="1510919282160" />
-    </method>
-  </configuration>
-</component>
\ No newline at end of file
diff --git a/.idea/runConfigurations/Step_5___Solution.xml b/.idea/runConfigurations/Step_5___Solution.xml
deleted file mode 100644
index a330ff3..0000000
--- a/.idea/runConfigurations/Step_5___Solution.xml
+++ /dev/null
@@ -1,51 +0,0 @@
-<component name="ProjectRunConfigurationManager">
-  <configuration default="false" name="Step 5 - Solution" type="AndroidRunConfigurationType" factoryName="Android App" activateToolWindowBeforeRun="false">
-    <module name="app" />
-    <option name="DEPLOY" value="true" />
-    <option name="ARTIFACT_NAME" value="" />
-    <option name="PM_INSTALL_OPTIONS" value="" />
-    <option name="ACTIVITY_EXTRA_FLAGS" value="" />
-    <option name="MODE" value="specific_activity" />
-    <option name="CLEAR_LOGCAT" value="false" />
-    <option name="SHOW_LOGCAT_AUTOMATICALLY" value="false" />
-    <option name="SKIP_NOOP_APK_INSTALLATIONS" value="true" />
-    <option name="FORCE_STOP_RUNNING_APP" value="true" />
-    <option name="TARGET_SELECTION_MODE" value="SHOW_DIALOG" />
-    <option name="USE_LAST_SELECTED_DEVICE" value="true" />
-    <option name="PREFERRED_AVD" value="" />
-    <option name="SELECTED_CLOUD_MATRIX_CONFIGURATION_ID" value="-1" />
-    <option name="SELECTED_CLOUD_MATRIX_PROJECT_ID" value="" />
-    <option name="DEBUGGER_TYPE" value="Auto" />
-    <Auto>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Auto>
-    <Hybrid>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Hybrid>
-    <Java />
-    <Native>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Native>
-    <Profilers>
-      <option name="ADVANCED_PROFILING_ENABLED" value="false" />
-    </Profilers>
-    <option name="DEEP_LINK" value="" />
-    <option name="ACTIVITY_CLASS" value="com.example.android.persistence.codelab.step5_solution.CustomResultUserActivity" />
-    <method>
-      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-      <option name="com.android.instantApps.provision.BeforeRunTask" enabled="true" clearCache="false" clearProvisionedDevices="false" myTimestamp="1510919282160" />
-    </method>
-  </configuration>
-</component>
\ No newline at end of file
diff --git a/.idea/vcs.xml b/.idea/vcs.xml
new file mode 100644
index 0000000..94a25f7
--- /dev/null
+++ b/.idea/vcs.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$" vcs="Git" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/app/build.gradle b/app/build.gradle
index f272c07..cba1d4c 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -18,7 +18,7 @@ apply plugin: 'com.android.application'
 
 android {
     compileSdkVersion 27
-    buildToolsVersion "27.0.0"
+    buildToolsVersion '27.0.3'
     defaultConfig {
         applicationId 'com.example.android.codelabs.persistence'
         minSdkVersion 21
@@ -46,19 +46,19 @@ android {
 }
 
 dependencies {
-    compile fileTree(include: ['*.jar'], dir: 'libs')
-    androidTestCompile('com.android.support.test.espresso:espresso-core:' + rootProject.espressoVersion, {
+    implementation fileTree(include: ['*.jar'], dir: 'libs')
+    androidTestImplementation('com.android.support.test.espresso:espresso-core:' + rootProject.espressoVersion, {
         exclude group: 'com.android.support', module: 'support-annotations'
     })
 
-    compile 'com.android.support:appcompat-v7:' + rootProject.supportLibVersion
-    compile 'com.android.support:cardview-v7:' + rootProject.supportLibVersion
-    compile 'com.android.support:recyclerview-v7:' + rootProject.supportLibVersion
-    compile 'com.android.support:support-v4:' + rootProject.supportLibVersion
+    implementation 'com.android.support:appcompat-v7:' + rootProject.supportLibVersion
+    implementation 'com.android.support:cardview-v7:' + rootProject.supportLibVersion
+    implementation 'com.android.support:recyclerview-v7:' + rootProject.supportLibVersion
+    implementation 'com.android.support:support-v4:' + rootProject.supportLibVersion
 
-    testCompile 'junit:junit:4.12'
-    compile 'android.arch.lifecycle:extensions:' + rootProject.archLifecycleVersion
-    compile 'android.arch.persistence.room:runtime:' + rootProject.archRoomVersion
+    testImplementation 'junit:junit:4.12'
+    implementation 'android.arch.lifecycle:extensions:' + rootProject.archLifecycleVersion
+    implementation 'android.arch.persistence.room:runtime:' + rootProject.archRoomVersion
     annotationProcessor 'android.arch.lifecycle:compiler:' + rootProject.archLifecycleVersion
     annotationProcessor 'android.arch.persistence.room:compiler:' + rootProject.archRoomVersion
 }
diff --git a/build.gradle b/build.gradle
index 2a6ce4e..e140b2c 100644
--- a/build.gradle
+++ b/build.gradle
@@ -22,7 +22,7 @@ buildscript {
         google()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.0.0'
+        classpath 'com.android.tools.build:gradle:3.1.4'
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index a052f6e..edce5fc 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,6 +1,6 @@
-#Mon Nov 13 23:43:41 GMT 2017
+#Fri Sep 14 11:27:18 BRT 2018
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.1-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.4-all.zip