b/325372861 Add client for Cloud Identity Groups API (#289)

The client isn't used yet, but will be needed in the future.

sources/pom.xml

@@ -89,6 +89,12 @@
       <artifactId>google-api-services-admin-directory</artifactId>
       <version>directory_v1-rev20240220-2.0.0</version>
     </dependency>
+    <dependency>
+      <groupId>com.google.apis</groupId>
+      <artifactId>google-api-services-cloudidentity</artifactId>
+      <version>v1-rev20240206-2.0.0</version>
+    </dependency>
+
     <dependency>
       <groupId>com.google.code.gson</groupId>
       <artifactId>gson</artifactId>

sources/src/main/java/com/google/solutions/jitaccess/core/AccessException.java

@@ -22,6 +22,10 @@
 package com.google.solutions.jitaccess.core;
 
 public abstract class AccessException extends Exception {
+  public AccessException(String message) {
+    super(message);
+  }
+
   public AccessException(String message, Exception inner) {
     super(message, inner);
   }

sources/src/main/java/com/google/solutions/jitaccess/core/GroupEmail.java

@@ -0,0 +1,71 @@
+//
+// Copyright 2024 Google LLC
+//
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+//
+
+package com.google.solutions.jitaccess.core;
+
+import com.google.common.base.Preconditions;
+
+import java.util.Objects;
+
+/**
+ * Email address of a group.
+ */
+public class GroupEmail implements Comparable<GroupEmail> {
+  public final String email;
+
+  public GroupEmail(String email) {
+    Preconditions.checkNotNull(email, "email");
+    this.email = email;
+  }
+
+  @Override
+  public String toString() {
+    return this.email;
+  }
+
+  // -------------------------------------------------------------------------
+  // Equality.
+  // -------------------------------------------------------------------------
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+
+    GroupEmail GroupEmail = (GroupEmail) o;
+    return email.equals(GroupEmail.email);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(email);
+  }
+
+  @Override
+  public int compareTo(GroupEmail o) {
+    return this.email.compareTo(o.email);
+  }
+}

sources/src/main/java/com/google/solutions/jitaccess/core/GroupId.java

@@ -0,0 +1,82 @@
+//
+// Copyright 2024 Google LLC
+//
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+//
+
+package com.google.solutions.jitaccess.core;
+
+import com.google.common.base.Preconditions;
+
+import java.util.Objects;
+
+/**
+ * Primary email address and unique ID of a group.
+ */
+public class GroupId extends UserEmail {
+  private static final String GROUPS_PREFIX = "groups/";
+
+  public final transient String id;
+
+  public GroupId(String id, String email) {
+    super(email);
+
+    Preconditions.checkNotNull(id, "id");
+
+    if (id.startsWith(GROUPS_PREFIX)) {
+      id = id.substring(GROUPS_PREFIX.length());
+    }
+
+    this.id = id;
+  }
+
+  public GroupId(String id, GroupEmail email) {
+    this(id, email.email);
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+
+    if (!super.equals(o)) {
+      return false;
+    }
+
+    GroupId GroupId = (GroupId) o;
+    return this.id.equals(GroupId.id);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(super.hashCode(), id);
+  }
+
+  /**
+   * @return ID in groups/ID format.
+   */
+  @Override
+  public String toString() {
+    return String.format("%s%s", GROUPS_PREFIX, this.id); //TODO: test
+  }
+}