public FunctionInfo registerFunction(
      String functionName, Class<?> udfClass, FunctionResource... resources) {
    FunctionType functionType = isNative ? FunctionType.BUILTIN : FunctionType.TEMPORARY;
    return registerFunction(functionName, functionType, udfClass, resources);
  }
Registers the appropriate kind of temporary function based on a class's
type.

@param functionName name under which to register function
@param udfClass     class implementing UD[A|T]F
@return true if udfClass's type was recognized (so registration
        succeeded); false otherwise
ql/src/java/org/apache/hadoop/hive/ql/exec/Registry.java