@Nullable
  public <T> T execute (@Nonnull final HttpUriRequest aRequest,
                        @Nonnull final ResponseHandler <T> aResponseHandler) throws IOException
  {
    return execute (aRequest, (HttpContext) null, aResponseHandler);
  }
@ Nullable public < T > T execute ( @ Nonnull final HttpUriRequest aRequest , @ Nonnull final ResponseHandler < T > aResponseHandler ) throws IOException { return execute ( aRequest , ( HttpContext ) null , aResponseHandler ) ; }
Execute the provided request without any special context. The response
handler is invoked as a callback. This method automatically cleans up all
used resources and as such is preferred over the execute methods returning
the CloseableHttpResponse.

@param aRequest
The request to be executed. May not be <code>null</code>.
@param aResponseHandler
The response handler to be executed. May not be <code>null</code>.
@return The evaluated response of the response handler. May be
<code>null</code>.
@throws IOException
In case of error
@throws IllegalStateException
If this manager was already closed!
@param <T>
return type