Restful Data-Source to support header

Headers are name/value pairs that appear in both request and response messages. Some of the headers are shown below.

• The Accept request-header field can be used to specify certain media types which are acceptable for the response. Accept headers can be used to indicate that the request is specifically limited to a small set of desired types, as in the case of a request for an in-line image.
• The Accept-Charset request-header field can be used to indicate what character sets are acceptable for the response.
• The Accept-Language request-header field is similar to Accept, but restricts the set of natural languages that are preferred as a response to the request. For example here we have shown the Accept-Language request-header to accept json.