public void getField_locked() throws Exception
{
Type type = new Type( "blah" );
assertNotNull( type.getField( "a" ) );
assertNotNull( type.getField( "b" ) );
type.lock();
assertNotNull( type.getField( "a" ) );
assertNotNull( type.getField( "b" ) );
assertNull( type.getField( "x" ) );
assertNull( type.getField( "y" ) );
}