code: @Override
      public DeleteDBSubnetGroupResult deleteDBSubnetGroup(DeleteDBSubnetGroupRequest request) {
          request = beforeClientExecution(request);
          return executeDeleteDBSubnetGroup(request);
      }
docs: <p>
  Deletes a DB subnet group.
  </p>
  <note>
  <p>
  The specified database subnet group must not be associated with any DB instances.
  </p>
  </note>
  
  @param deleteDBSubnetGroupRequest
  @return Result of the DeleteDBSubnetGroup operation returned by the service.
  @throws InvalidDBSubnetGroupStateException
  The DB subnet group cannot be deleted because it is in use.
  @throws InvalidDBSubnetStateException
  The DB subnet is not in the <i>available</i> state.
  @throws DBSubnetGroupNotFoundException
  <i>DBSubnetGroupName</i> does not refer to an existing DB subnet group.
  @sample AmazonNeptune.DeleteDBSubnetGroup
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/neptune-2014-10-31/DeleteDBSubnetGroup" target="_top">AWS
  API Documentation</a>