code: static void addOperationAddress(final ModelNode operation, final PathAddress base, final String key, final String value) {
          operation.get(OP_ADDR).set(base.append(key, value).toModelNode());
      }
docs: Appends the key and value to the address and sets the address on the operation.
  
  @param operation the operation to set the address on
  @param base      the base address
  @param key       the key for the new address
  @param value     the value for the new address