How to use

getField

method

in

com.google.protobuf.Message$Builder

@Override
public IRepeatedFieldValueBuilder<E> remove(final int index) {
 @SuppressWarnings("unchecked")
 final List<E> list = (List<E>) parent.getField(field);
 if ((list == null) || (index < 0) || (index >= list.size())) {
  throw new IndexOutOfBoundsException();
 }
 final List<E> newList = new ArrayList<E>(list);
 newList.remove(index);
 parent.setField(field, newList);
 changedIndex = index;
 return this;
}

@Override
public IRepeatedFieldValueBuilder<E> add(final int index, final E element) {
 @SuppressWarnings("unchecked")
 final List<E> list = (List<E>) parent.getField(field);
 if (((list == null) && (index != 0)) || (index < 0)
   || ((list != null) && (index > list.size()))) {
  throw new IndexOutOfBoundsException();
 }
 final List<E> newList = list == null ? new ArrayList<E>() : new ArrayList<E>(list);
 newList.add(index, element);
 parent.setField(field, newList);
 changedIndex = index;
 return this;
}

 /**
  * Helper method to get an {@link Map} from message builder for the map field. The map returned is
  * an immutable copy, to add entries to a map field use {@link
  * ConfigSource#putMapEntry(com.google.protobuf.Message.Builder, FieldDescriptor, Object, Object)}
  */
 @SuppressWarnings("unchecked")
 private static ImmutableMap<Object, Object> getMapFromProtoMapBuilder(
   Message.Builder builder, FieldDescriptor field) {
  List<Message> entries = (List<Message>) builder.getField(field);
  ImmutableMap.Builder<Object, Object> mapBuilder = ImmutableMap.builder();
  for (Message entry : entries) {
   Object key = entry.getField(entry.getDescriptorForType().findFieldByName("key"));
   Object value = entry.getField(entry.getDescriptorForType().findFieldByName("value"));
   mapBuilder.put(key, value);
  }
  return mapBuilder.build();
 }
}

/**
 * Constructs a sub-builder for given field and calls the action on it. After the action's
 * processing, the sub-message will be build and stored into the field of this builder.
 * Moreover, update locations of the sub-builder are integrated into this builder.
 */
public Builder withBuilder(FieldDescriptor field, BuildAction action) {
 // Construct a fresh builder for the given field and merge in the current value. As we depend
 // on message identity, we need to control this builder directly, so can't use implicit
 // building via getFieldBuilder. A builder created by getFieldBuilder as build() called
 // when the parent is called, resulting in a different message identity.
 Message currentValue = (Message) configBuilder.getField(field);
 Message.Builder protoBuilder = configBuilder.newBuilderForField(field);
 protoBuilder.mergeFrom(currentValue);
 // Construct config builder, and let the action process it.
 Builder fieldConfigBuilder = new Builder(currentValue, protoBuilder, locations);
 action.accept(fieldConfigBuilder);
 // Build config, which updates the location mapping, and update proto builder.
 ConfigSource fieldConfig = fieldConfigBuilder.build();
 configBuilder.setField(field, fieldConfig.getConfig());
 return this;
}

/**
 * Constructs a sub-builder for given field and calls the action on it. After the action's
 * processing, the sub-message will be build and stored into the field of this builder.
 * Moreover, update locations of the sub-builder are integrated into this builder.
 */
public Builder withBuilder(FieldDescriptor field, BuildAction action) {
 // Construct a fresh builder for the given field and merge in the current value. As we depend
 // on message identity, we need to control this builder directly, so can't use implicit
 // building via getFieldBuilder. A builder created by getFieldBuilder as build() called
 // when the parent is called, resulting in a different message identity.
 Message currentValue = (Message) configBuilder.getField(field);
 Message.Builder protoBuilder = configBuilder.newBuilderForField(field);
 protoBuilder.mergeFrom(currentValue);
 // Construct config builder, and let the action process it.
 Builder fieldConfigBuilder = new Builder(currentValue, protoBuilder, locations);
 action.accept(fieldConfigBuilder);
 // Build config, which updates the location mapping, and update proto builder.
 ConfigSource fieldConfig = fieldConfigBuilder.build();
 configBuilder.setField(field, fieldConfig.getConfig());
 return this;
}

@Override
public Object getValue(final ELContext context, final Object base, final Object property) {
 if (context == null) {
  throw new NullPointerException();
 }
 if ((property != null) && resolveType(base)) {
  context.setPropertyResolved(base, property);
  final Message.Builder builder = (Message.Builder) base;
  final FieldDescriptor field = getPropertyFieldDescriptor(builder, property);
  if (field.isRepeated()) {
   return getBuilderForRepeatedField(builder, field);
  } else {
   if (field.getJavaType() == JavaType.MESSAGE) {
    return builder.getFieldBuilder(field);
   } else {
    return builder.getField(field);
   }
  }
 }
 return null;
}

 /**
  * Helper method to get an {@link Map} from message builder for the map field. The map returned is
  * an immutable copy, to add entries to a map field use {@link
  * ConfigSource#putMapEntry(com.google.protobuf.Message.Builder, FieldDescriptor, Object, Object)}
  */
 @SuppressWarnings("unchecked")
 private static ImmutableMap<Object, Object> getMapFromProtoMapBuilder(
   Message.Builder builder, FieldDescriptor field) {
  List<Message> entries = (List<Message>) builder.getField(field);
  ImmutableMap.Builder<Object, Object> mapBuilder = ImmutableMap.builder();
  for (Message entry : entries) {
   Object key = entry.getField(entry.getDescriptorForType().findFieldByName("key"));
   Object value = entry.getField(entry.getDescriptorForType().findFieldByName("value"));
   mapBuilder.put(key, value);
  }
  return mapBuilder.build();
 }
}

@SuppressWarnings("unchecked")
private static void putMapEntry(
  Message.Builder builder, FieldDescriptor field, Object key, Object value) {
 Message.Builder entryBuilder = builder.newBuilderForField(field);
 FieldDescriptor keyField = entryBuilder.getDescriptorForType().findFieldByName("key");
 FieldDescriptor valueField = entryBuilder.getDescriptorForType().findFieldByName("value");
 entryBuilder.setField(keyField, key);
 entryBuilder.setField(valueField, value);
 List<Message> entries =
   removeEntryWithKeyIfPresent((List<Message>) builder.getField(field), key);
 entries.add(entryBuilder.build());
 builder.setField(field, entries);
}

public Object getField(Descriptors.FieldDescriptor field) {
 return builder.getField(field);
}

@Override
public Object getField(Descriptors.FieldDescriptor field) {
 return builder.getField(field);
}

@SuppressWarnings("unchecked")
@Override
public List<? extends E> getList() {
 return (List<? extends E>) parent.getField(field);
}

@SuppressWarnings("unchecked")
private static void putMapEntry(
  Message.Builder builder, FieldDescriptor field, Object key, Object value) {
 Message.Builder entryBuilder = builder.newBuilderForField(field);
 FieldDescriptor keyField = entryBuilder.getDescriptorForType().findFieldByName("key");
 FieldDescriptor valueField = entryBuilder.getDescriptorForType().findFieldByName("value");
 entryBuilder.setField(keyField, key);
 entryBuilder.setField(valueField, value);
 List<Message> entries =
   removeEntryWithKeyIfPresent((List<Message>) builder.getField(field), key);
 entries.add(entryBuilder.build());
 builder.setField(field, entries);
}

@Override
public Object getField(Descriptors.FieldDescriptor field) {
 return builder.getField(field);
}

/** helper method to handle {@code builder} and {@code extensions}. */
private static Message getOriginalMessage(
  Message.Builder builder,
  FieldSet<FieldDescriptor> extensions,
  FieldDescriptor field) {
 if (builder != null) {
  return (Message) builder.getField(field);
 } else {
  return (Message) extensions.getField(field);
 }
}