rest-assured/src/main/java/io/restassured/RestAssured.java
public static AuthenticationScheme oauth2(String accessToken) {
        PreemptiveOAuth2HeaderScheme myScheme = new PreemptiveOAuth2HeaderScheme();
        myScheme.setAccessToken(accessToken);
        return myScheme;
    }
public static AuthenticationScheme oauth2(String accessToken) {
        PreemptiveOAuth2HeaderScheme myScheme = new PreemptiveOAuth2HeaderScheme();
        myScheme.setAccessToken(accessToken);
        return myScheme;
    }
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 The access token to use
@return The authentication scheme