code: public void defineField(int modifier, String fieldName, TypeMirror type)
      {
          DeclaredType dt = (DeclaredType)asType();
          VariableBuilder builder = new VariableBuilder(this, fieldName, dt.getTypeArguments(), typeParameterMap);
          builder.addModifiers(modifier);
          builder.setType(type);
          FieldInfo fieldInfo = new FieldInfo(this, builder.getVariableElement());
          addFieldInfo(fieldInfo);
          fieldInfo.readyToWrite();
      }
docs: Define a new field.
  @param modifier
  @param fieldName
  @param type