public Builder setArgumentTypes(String ... types) {
      for (int i = 0; i < types.length; i++) {
        argTypes[i] = ArgumentType.getType(types[i]);
      }
      return this;
    }
Builder builds a {@link Descriptor} object. Setter methods are provided to set the {@link Mode}, number
of arguments, argument types and expression types for each argument.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/VectorExpressionDescriptor.java