this JSON structure can be created by following PHP code
$json = json_encode(array(
"client" => array(
"build" => "1.0",
"name" => "xxxxxx",
"version" => "1.0"
),
"protocolVersion" => 4,
"data" => array(
"distributorId" => "xxxx",
"distributorPin" => "xxxx",
"locale" => "en-US"
)
));
see json_encode