code: public String buildAuthorizationHeaderValue(HttpMethod method, URI targetUrl, Map<String, String> oauthParameters, MultiValueMap<String, String> additionalParameters, String consumerSecret, String tokenSecret) {
  		StringBuilder header = new StringBuilder();
  		header.append("OAuth ");
  		for (Entry<String, String> entry : oauthParameters.entrySet()) {
  			header.append(oauthEncode(entry.getKey())).append("=\"").append(oauthEncode(entry.getValue())).append("\", ");
  		}
  		MultiValueMap<String, String> collectedParameters = new LinkedMultiValueMap<String, String>((int) ((oauthParameters.size() + additionalParameters.size()) / .75 + 1));
  		collectedParameters.setAll(oauthParameters);
  		collectedParameters.putAll(additionalParameters);		
  		String baseString = buildBaseString(method, getBaseStringUri(targetUrl), collectedParameters);
  		String signature = calculateSignature(baseString, consumerSecret, tokenSecret);
  		header.append(oauthEncode("oauth_signature")).append("=\"").append(oauthEncode(signature)).append("\"");
  		return header.toString();
  	}
docs: Builds the authorization header.
  The elements in additionalParameters are expected to not be encoded.