code: public static ModelNode createWriteAttributeRequest(String attributeName, String attributeValue, Address address) {
          final ModelNode op = createRequest(WRITE_ATTRIBUTE, address);
          op.get(NAME).set(attributeName);
          setPossibleExpression(op, VALUE, attributeValue);
          return op;
      }
docs: Convienence method that allows you to create request that writes a single attribute's
  string value to a resource.
  
  @param attributeName the name of the attribute whose value is to be written
  @param attributeValue the attribute value that is to be written
  @param address identifies the resource
  @return the request