Added a null check to GitlabGroup#setLdapAccess. This resolves a...

Added a null check to GitlabGroup#setLdapAccess. This resolves a NullPointerException that was encountered when unmarshalling a a GitlabGroup JSON object with a null ldap_access attribute.

src/main/java/org/gitlab/api/models/GitlabGroup.java

@@ -53,6 +53,8 @@ public class GitlabGroup {
     }
 
     public void setLdapAccess(GitlabAccessLevel ldapGitlabAccessLevel) {
-       this.ldapAccess = ldapGitlabAccessLevel.accessValue;
+        if (ldapGitlabAccessLevel != null) {
+            this.ldapAccess = ldapGitlabAccessLevel.accessValue;
+        }
     }
 }

src/test/java/org/gitlab/api/models/GitlabGroupTest.java

+package org.gitlab.api.models;
+
+import org.junit.Test;
+
+/**
+ * Tests for {@link GitlabGroup}
+ */
+public class GitlabGroupTest {
+
+    @Test
+    public void setLdapAccessHandlesNull() {
+        GitlabGroup group = new GitlabGroup();
+        group.setLdapAccess(null);
+    }
+
+}