code: private void assertPropertyIsIndexed(final PropertyKey key) {
  
  		if (key != null && !key.isIndexed() && key instanceof AbstractPrimitiveProperty) {
  
  			final Class declaringClass = key.getDeclaringClass();
  			String className           = "";
  
  			if (declaringClass != null) {
  
  				className = declaringClass.getSimpleName() + ".";
  			}
  
  			logger.warn("Non-indexed property key {}{} is used in query. This can lead to performance problems in large databases.", className, key.jsonName());
  		}
  	}
docs: ----- private methods ----