public static void registerUDF(boolean isNative, String functionName,
Class<? extends UDF> UDFClass, boolean isOperator, String displayName) {
if (UDF.class.isAssignableFrom(UDFClass)) {
FunctionInfo fI = new FunctionInfo(isNative, displayName,
new GenericUDFBridge(displayName, isOperator, UDFClass));
mFunctions.put(functionName.toLowerCase(), fI);
} else {
throw new RuntimeException("Registering UDF Class " + UDFClass
+ " which does not extend " + UDF.class);
}