Remove null assignability to function arguments for Protobuf messages

PiperOrigin-RevId: 836803181

Author: l46kok

runtime/src/main/java/dev/cel/runtime/BUILD.bazel

@@ -1174,7 +1174,6 @@ java_library(
         "//:auto_value",
         "@maven//:com_google_errorprone_error_prone_annotations",
         "@maven//:com_google_guava_guava",
-        "@maven//:com_google_protobuf_protobuf_java",
     ],
 )
 
@@ -1189,7 +1188,6 @@ cel_android_library(
         "//:auto_value",
         "@maven//:com_google_errorprone_error_prone_annotations",
         "@maven_android//:com_google_guava_guava",
-        "@maven_android//:com_google_protobuf_protobuf_javalite",
     ],
 )
 

runtime/src/main/java/dev/cel/runtime/CelResolvedOverload.java

@@ -17,7 +17,6 @@
 import com.google.auto.value.AutoValue;
 import com.google.common.collect.ImmutableList;
 import com.google.errorprone.annotations.Immutable;
-import com.google.protobuf.MessageLite;
 import java.util.List;
 import java.util.Map;
 
@@ -89,9 +88,7 @@ boolean canHandle(Object[] arguments) {
       if (arg == null) {
         // null can be assigned to messages, maps, and to objects.
         // TODO: Remove null special casing
-        if (paramType != Object.class
-            && !MessageLite.class.isAssignableFrom(paramType)
-            && !Map.class.isAssignableFrom(paramType)) {
+        if (paramType != Object.class && !Map.class.isAssignableFrom(paramType)) {
           return false;
         }
         continue;

runtime/src/test/java/dev/cel/runtime/CelLateFunctionBindingsTest.java

@@ -130,16 +130,13 @@ public void findOverload_nullPrimitiveArg_isEmpty() throws Exception {
   }
 
   @Test
-  public void findOverload_nullMessageArg_returnsOverload() throws Exception {
+  public void findOverload_nullMessageArg_isEmpty() throws Exception {
     CelLateFunctionBindings bindings =
         CelLateFunctionBindings.from(
             CelFunctionBinding.from("identity_msg", TestAllTypes.class, (arg) -> arg));
     Optional<CelResolvedOverload> overload =
         bindings.findOverloadMatchingArgs(
             "identity", ImmutableList.of("identity_msg"), new Object[] {null});
-    assertThat(overload).isPresent();
-    assertThat(overload.get().getOverloadId()).isEqualTo("identity_msg");
-    assertThat(overload.get().getParameterTypes()).containsExactly(TestAllTypes.class);
-    assertThat(overload.get().getDefinition().apply(new Object[] {null})).isNull();
+    assertThat(overload).isEmpty();
   }
 }

runtime/src/test/java/dev/cel/runtime/CelResolvedOverloadTest.java

@@ -42,11 +42,11 @@ public void canHandle_matchingTypes_returnsTrue() {
   }
 
   @Test
-  public void canHandle_nullMessageType_returnsTrue() {
+  public void canHandle_nullMessageType_returnsFalse() {
     CelResolvedOverload overload =
         CelResolvedOverload.of(
             "identity", (args) -> args[0], /* isStrict= */ true, TestAllTypes.class);
-    assertThat(overload.canHandle(new Object[] {null})).isTrue();
+    assertThat(overload.canHandle(new Object[] {null})).isFalse();
   }
 
   @Test