protected String addImports(List<String> classNames) {
    StringBuilder code = new StringBuilder();
    for (String className: classNames) {
      code.append("import ").append(className).append(";\n");
    }
    return code.toString();
  }
@Test
    public void testAddImports() {
        MessageCodeGen messageCodeGen = new MessageCodeGen();
        ArrayList<String> inputs = new ArrayList<>();
        inputs.add("com.pinot.MessageCodeGen");
        inputs.add("com.pinot.Test");
        assertEquals(
            messageCodeGen.addImports(inputs), "import com.pinot.MessageCodeGen;\n" + "import com.pinot.Test;\n");
    }