String descriptor(boolean includeThis) {
    StringBuilder result = new StringBuilder();
    result.append("(");
    if (includeThis) {
      result.append(declaringType.name);
    }
    for (TypeId t : parameters.types) {
      result.append(t.name);
    }
    result.append(")");
    result.append(returnType.name);
    return result.toString();
  }
Returns a descriptor like "(Ljava/lang/Class;[I)Ljava/lang/Object;".
android/android_framework/dex-maker/src/main/java/com/android/dx/MethodId.java