public static void main(String[] args) {
MessageType message1;
MessageType message2;
PrimitiveType c = new PrimitiveType(Repetition.OPTIONAL, PrimitiveTypeName.INT32, "c");
GroupType b = new GroupType(Repetition.REQUIRED, "b");
GroupType a = new GroupType(Repetition.OPTIONAL, "a", b);
message1 = new MessageType("root", a);
PrimitiveType c2 = new PrimitiveType(Repetition.OPTIONAL, PrimitiveTypeName.INT32, "d");
GroupType b2 = new GroupType(Repetition.OPTIONAL, "b", c2);
GroupType a2 = new GroupType(Repetition.OPTIONAL, "a", b2);
message2 = new MessageType("root", a2);
MessageType message3 = message1.union(message2);
StringBuilder builder = new StringBuilder();