Fixed compiler warnings.

Author: gmessner

src/test/java/org/gitlab4j/api/TestGitLabLogin.java

@@ -88,7 +88,7 @@ public void beforeMethod() {
         assumeTrue(problems != null && problems.isEmpty());
     }
 
-    @SuppressWarnings({ "deprecation" })
+    @SuppressWarnings("deprecation")
     @Test
     public void testSession() throws GitLabApiException {
 

src/test/java/org/gitlab4j/api/TestProjectApi.java

@@ -38,7 +38,6 @@
 import org.gitlab4j.api.models.AccessLevel;
 import org.gitlab4j.api.models.Group;
 import org.gitlab4j.api.models.Project;
-import org.gitlab4j.api.models.User;
 import org.gitlab4j.api.models.Visibility;
 import org.junit.AfterClass;
 import org.junit.Before;

src/test/java/org/gitlab4j/api/TestUserApi.java

@@ -15,7 +15,6 @@
 import javax.ws.rs.core.Response;
 
 import org.gitlab4j.api.GitLabApi.ApiVersion;
-import org.gitlab4j.api.models.Group;
 import org.gitlab4j.api.models.ImpersonationToken;
 import org.gitlab4j.api.models.ImpersonationToken.Scope;
 import org.gitlab4j.api.models.SshKey;