Allow encoder registration override. (#1039)

* Allow encoder registration override.

Instead of throwing an error, we allow encoders to override previously registered ones.

Author: rlazo

encoders/firebase-encoders-json/api.txt

@@ -37,6 +37,20 @@ package com.google.firebase.encoders {
 
 }
 
+package com.google.firebase.encoders.annotations {
+
+  @java.lang.annotation.Retention(java.lang.annotation.RetentionPolicy.CLASS) public @interface Encodable {
+  }
+
+  @java.lang.annotation.Retention(java.lang.annotation.RetentionPolicy.CLASS) public static @interface Encodable.Field {
+    method public abstract String name() default "";
+  }
+
+  @java.lang.annotation.Retention(java.lang.annotation.RetentionPolicy.CLASS) public static @interface Encodable.Ignore {
+  }
+
+}
+
 package com.google.firebase.encoders.config {
 
   public interface Configurator {

encoders/firebase-encoders-json/src/json/java/com/google/firebase/encoders/json/JsonDataEncoderBuilder.java

@@ -68,21 +68,19 @@ public JsonDataEncoderBuilder() {
   @Override
   public <T> JsonDataEncoderBuilder registerEncoder(
       @NonNull Class<T> clazz, @NonNull ObjectEncoder<? super T> objectEncoder) {
-    if (objectEncoders.containsKey(clazz)) {
-      throw new IllegalArgumentException("Encoder already registered for " + clazz.getName());
-    }
     objectEncoders.put(clazz, objectEncoder);
+    // Remove it from the other map if present.
+    valueEncoders.remove(clazz);
     return this;
   }
 
   @NonNull
   @Override
   public <T> JsonDataEncoderBuilder registerEncoder(
       @NonNull Class<T> clazz, @NonNull ValueEncoder<? super T> encoder) {
-    if (valueEncoders.containsKey(clazz)) {
-      throw new IllegalArgumentException("Encoder already registered for " + clazz.getName());
-    }
     valueEncoders.put(clazz, encoder);
+    // Remove it from the other map if present.
+    objectEncoders.remove(clazz);
     return this;
   }
 

encoders/firebase-encoders-json/src/test/java/com/google/firebase/encoders/json/JsonValueObjectEncoderContextTest.java

@@ -57,6 +57,43 @@ static class InnerDummyClass {
     static InnerDummyClass INSTANCE = new InnerDummyClass();
   }
 
+  @Test
+  public void testRegisterOverride() throws IOException, EncodingException {
+    ObjectEncoder<DummyClass> objectEncoder =
+        (o, ctx) -> {
+          ctx.add("Inner", InnerDummyClass.INSTANCE);
+        };
+    ObjectEncoder<InnerDummyClass> innerObjectEncoder =
+        (o, ctx) -> {
+          ctx.add("Name", "innerClass");
+        };
+    ValueEncoder<InnerDummyClass> innerValueEncoder =
+        (o, ctx) -> {
+          ctx.add(1234);
+        };
+
+    String result =
+        new JsonDataEncoderBuilder()
+            .registerEncoder(DummyClass.class, objectEncoder)
+            .registerEncoder(InnerDummyClass.class, innerObjectEncoder)
+            .registerEncoder(InnerDummyClass.class, innerValueEncoder)
+            .build()
+            .encode(DummyClass.INSTANCE);
+
+    assertThat(result).isEqualTo("{\"Inner\":1234}");
+
+    // Invert the logic
+    result =
+        new JsonDataEncoderBuilder()
+            .registerEncoder(DummyClass.class, objectEncoder)
+            .registerEncoder(InnerDummyClass.class, innerValueEncoder)
+            .registerEncoder(InnerDummyClass.class, innerObjectEncoder)
+            .build()
+            .encode(DummyClass.INSTANCE);
+
+    assertThat(result).isEqualTo("{\"Inner\":{\"Name\":\"innerClass\"}}");
+  }
+
   @Test
   public void testEncodingPrimitiveTypes() throws IOException, EncodingException {
     ObjectEncoder<DummyClass> objectEncoder =