field = new Field();
field.setVisibility(JavaVisibility.PROTECTED);
field.setType(FullyQualifiedJavaType.getBooleanPrimitiveInstance());
field.setName("distinct"); //$NON-NLS-1$
addFieldComment(field, "是否相异");
topLevelClass.addField(field);
// add field, getter, setter for orderby clause
field = new Field();
field.setVisibility(JavaVisibility.PROTECTED);
field.setType(FullyQualifiedJavaType.getStringInstance());