add SignInWithCustomToken to FirebaseAuth api

Author: anotherdev

firebase-auth-rest/core/src/main/java/com/anotherdev/firebase/auth/FirebaseAuth.java

@@ -45,6 +45,10 @@ public interface FirebaseAuth {
     @CheckReturnValue
     Single<SignInResponse> signInWithCredential(@NonNull IdpAuthCredential credential);
 
+    @NonNull
+    @CheckReturnValue
+    Single<SignInResponse> signInWithCustomToken(@NonNull String customToken);
+
     @NonNull
     @CheckReturnValue
     Single<SignInResponse> linkWithCredential(@NonNull FirebaseUser user, @NonNull IdpAuthCredential credential);

firebase-auth-rest/core/src/main/java/com/anotherdev/firebase/auth/rest/RestAuthProvider.java

@@ -15,6 +15,7 @@
 import com.anotherdev.firebase.auth.rest.api.model.ExchangeTokenRequest;
 import com.anotherdev.firebase.auth.rest.api.model.ImmutableSignInWithIdpRequest;
 import com.anotherdev.firebase.auth.rest.api.model.SignInAnonymouslyRequest;
+import com.anotherdev.firebase.auth.rest.api.model.SignInWithCustomTokenRequest;
 import com.anotherdev.firebase.auth.rest.api.model.SignInWithEmailPasswordRequest;
 import com.anotherdev.firebase.auth.rest.api.model.SignInWithIdpRequest;
 import com.anotherdev.firebase.auth.util.IdTokenParser;
@@ -124,6 +125,17 @@ public Single<SignInResponse> signInWithCredential(@NonNull IdpAuthCredential cr
         return performSignInWithCredential(builder, credential);
     }
 
+    @NonNull
+    @Override
+    public Single<SignInResponse> signInWithCustomToken(@NonNull String customToken) {
+        SignInWithCustomTokenRequest request = SignInWithCustomTokenRequest.builder()
+                .customToken(customToken)
+                .build();
+        return RestAuthApi.auth()
+                .signInWithCustomToken(request)
+                .map(this::saveCurrentUser);
+    }
+
     @NonNull
     @Override
     public Single<SignInResponse> linkWithCredential(@NonNull FirebaseUser user, @NonNull IdpAuthCredential credential) {