rest-assured/src/main/java/io/restassured/RestAssured.java
public static AuthenticationScheme oauth2(String accessToken, OAuthSignature signature) {
        OAuth2Scheme scheme = new OAuth2Scheme();
        scheme.setAccessToken(accessToken);
        scheme.setSignature(signature);
        return scheme;
    }
public static AuthenticationScheme oauth2(String accessToken, OAuthSignature signature) {
        OAuth2Scheme scheme = new OAuth2Scheme();
        scheme.setAccessToken(accessToken);
        scheme.setSignature(signature);
        return scheme;
    }
OAuth sign the request. Note that this currently does not wait for a WWW-Authenticate challenge before sending the the OAuth header.
All requests to all domains will be signed for this instance.

@param accessToken
@param signature
@return The authentication scheme