private Stream<PluginProtos.CodeGeneratorResponse.File> handleMessageType(final DescriptorProtos.DescriptorProto messageTypeDesc) {
    String fileName = javaPackage.replace(".", "/") + "/" + messageTypeDesc.getName() + JAVA_EXTENSION;

    String builder_methods = messageTypeDesc.getFieldList().stream()
            .map(this::handleBuilderField)
            .filter(StringUtils::isNotBlank)
            .collect(Collectors.joining("\n\n"));

    List<PluginProtos.CodeGeneratorResponse.File> files = new ArrayList<>();
    if (StringUtils.isNotBlank(builder_methods)) {
        String builderScopeStr = builder_methods + "\n\n";

        files.add(PluginProtos.CodeGeneratorResponse.File
                .newBuilder()
                .setName(fileName)
                .setContent(builderScopeStr)
                .setInsertionPoint("builder_scope:" + fileDesc.getPackage() + "." + messageTypeDesc.getName())
                .build()
        );
    }

    String classScopeStr = messageTypeDesc.getFieldList().stream()
            .filter(field -> field.getLabel() != DescriptorProtos.FieldDescriptorProto.Label.LABEL_REPEATED)
            .map(this::handleClassField)
            .filter(StringUtils::isNotBlank)
            .collect(Collectors.joining("\n\n"));

    if (StringUtils.isNotBlank(classScopeStr)) {
        files.add(PluginProtos.CodeGeneratorResponse.File
                .newBuilder()
                .setName(fileName)
                .setContent(classScopeStr)
                .setInsertionPoint("class_scope:" + fileDesc.getPackage() + "." + messageTypeDesc.getName())
                .build()
        );
    }

    // create a new file for protoc to write
    return files.stream();
}