public static String insertIndentation(String content, String indent)
    {
        if (!content.startsWith(LINE_SEPARATOR))
            content = indent + content;
        return content.replace(LINE_SEPARATOR, LINE_SEPARATOR + indent);
    }
Kind of preprocessor for proto files. Able to extend one messages with fields from other ones.

@author Ivan Prisyazhniy, Igor Scherbak
@created Mar 9, 2012
protostuff-compiler/src/main/java/io/protostuff/compiler/ProtoToProtoCompiler.java