code: public TypeName getTypeParameter() {
  		if (typeName instanceof ParameterizedTypeName) {
  			ParameterizedTypeName temp = (ParameterizedTypeName) typeName;
  			return temp.typeArguments.get(0);
  		} else if (typeName instanceof ArrayTypeName) {
  			ArrayTypeName temp = (ArrayTypeName) typeName;
  			return temp.componentType;
  		}
  
  		return null;
  	}
docs: <p>
  if element is a ParameterizedTypeName or array, return the first type
  parameter or the component typeName. Otherwise null.
  </p>
  
  @return if element is a ParameterizedTypeName or array, return the first
  type parameter or the component typeName. Otherwise null.