question: private Response requireJSON ( IHTTPSession session ) { final Map < String , String > headers = session . getHeaders ( ) ; if ( ! APPLICATION_JSON . equals ( headers . get ( CONTENT_TYPE ) ) ) { return newFixedLengthResponse ( Response . Status . NOT_ACCEPTABLE , MIME_PLAINTEXT , "Set content-type to application/json" ) ; } else { return null ; } }
target:  Ensures that the supplied data has the "content-type" set to JSON