How to use

getRepeatedFieldBuilder

method

in

com.google.protobuf.Message$Builder

 /** Recursively crawls the proto message while clearing each field of type {@link Source}. */
 @VisibleForTesting
 static void stripSourceReferences(Message.Builder msg) {
  for (FieldDescriptor fieldDesc : msg.getAllFields().keySet()) {
   if (!fieldDesc.getJavaType().equals(JavaType.MESSAGE)) {
    continue;
   }

   if (fieldDesc.getMessageType().getFullName().equals(Source.getDescriptor().getFullName())) {
    msg.clearField(fieldDesc);
   } else {
    if (fieldDesc.isRepeated()) {
     int repeatCount = msg.getRepeatedFieldCount(fieldDesc);
     for (int i = 0; i < repeatCount; i++) {
      stripSourceReferences(msg.getRepeatedFieldBuilder(fieldDesc, i));
     }
    } else {
     stripSourceReferences(msg.getFieldBuilder(fieldDesc));
    }
   }
  }
 }
}

/**
 * Processes the deletion of children via a particular child field of the current node's
 * descriptor (e.g. fields within a message; nested message types within a message; etc).
 */
@Override public void processDeletedChildren(FieldDescriptor childFieldDesc) {
 Message.Builder parentBuilder = node();
 if (!toBeDeleted().isEmpty()) {
  if (getContainingFile() != null) {
   getContainingFile().processDeletedChildren(toBeDeleted());
  }
  List<Message.Builder> keepItems = new ArrayList<>();
  int fieldCount = parentBuilder.getRepeatedFieldCount(childFieldDesc);
  for (int i = 0; i < fieldCount; i++) {
   Message.Builder messageBuilder = parentBuilder.getRepeatedFieldBuilder(childFieldDesc, i);
   if (!toBeDeleted().contains(messageBuilder)) {
    keepItems.add(messageBuilder);
   }
  }
  toBeDeleted().clear();
  parentBuilder.clearField(childFieldDesc);
  for (Message.Builder newChild : keepItems) {
   parentBuilder.addRepeatedField(childFieldDesc, newChild.build());
  }
 }
}

/**
 * Processes the deletion of children via a particular child field of the current node's
 * descriptor (e.g. fields within a message; nested message types within a message; etc).
 */
@Override public void processDeletedChildren(FieldDescriptor childFieldDesc) {
 Message.Builder parentBuilder = node();
 if (!toBeDeleted().isEmpty()) {
  if (getContainingFile() != null) {
   getContainingFile().processDeletedChildren(toBeDeleted());
  }
  List<Message.Builder> keepItems = new ArrayList<>();
  int fieldCount = parentBuilder.getRepeatedFieldCount(childFieldDesc);
  for (int i = 0; i < fieldCount; i++) {
   Message.Builder messageBuilder = parentBuilder.getRepeatedFieldBuilder(childFieldDesc, i);
   if (!toBeDeleted().contains(messageBuilder)) {
    keepItems.add(messageBuilder);
   }
  }
  toBeDeleted().clear();
  parentBuilder.clearField(childFieldDesc);
  for (Message.Builder newChild : keepItems) {
   parentBuilder.addRepeatedField(childFieldDesc, newChild.build());
  }
 }
}

protected void visitRepeated(int fieldNumber) {
 BuilderVisitorNodeInfo parentInfo = ancestors.peek();
 Message.Builder parentBuilder = (Message.Builder) parentInfo.node();
 FieldDescriptor fieldDesc = parentBuilder.getDescriptorForType().findFieldByNumber(fieldNumber);
 if (fieldDesc == null) {
  throw new RuntimeException(
    String.format(
      "BuilderVisitor internal error - bad field number %d for type %s",
      fieldNumber, parentBuilder.getDescriptorForType().getFullName()));
 }
 int fieldCount = parentBuilder.getRepeatedFieldCount(fieldDesc);
 for (int i = 0; i < fieldCount; i++) {
  Message.Builder element = parentBuilder.getRepeatedFieldBuilder(fieldDesc, i);
  // If we got in here via a FileDescriptor, let it know where we are in the traversal so it
  // can build up its path <-> proto element mappings.
  if (currentFile != null) {
   currentFile.pushChildPath(element, fieldNumber, i);
  }
  try {
   visit(element);
  } finally {
   if (currentFile != null) {
    currentFile.popChildPath();
   }
  }
 }
 parentInfo.processDeletedChildren(fieldDesc);
}

protected void visitRepeated(int fieldNumber) {
 BuilderVisitorNodeInfo parentInfo = ancestors.peek();
 Message.Builder parentBuilder = (Message.Builder) parentInfo.node();
 FieldDescriptor fieldDesc = parentBuilder.getDescriptorForType().findFieldByNumber(fieldNumber);
 if (fieldDesc == null) {
  throw new RuntimeException(
    String.format(
      "BuilderVisitor internal error - bad field number %d for type %s",
      fieldNumber, parentBuilder.getDescriptorForType().getFullName()));
 }
 int fieldCount = parentBuilder.getRepeatedFieldCount(fieldDesc);
 for (int i = 0; i < fieldCount; i++) {
  Message.Builder element = parentBuilder.getRepeatedFieldBuilder(fieldDesc, i);
  // If we got in here via a FileDescriptor, let it know where we are in the traversal so it
  // can build up its path <-> proto element mappings.
  if (currentFile != null) {
   currentFile.pushChildPath(element, fieldNumber, i);
  }
  try {
   visit(element);
  } finally {
   if (currentFile != null) {
    currentFile.popChildPath();
   }
  }
 }
 parentInfo.processDeletedChildren(fieldDesc);
}