Add test objects used in tests.

For example, the o.s.d.g.tests.objects.geode.security.TestSecurityManager is a test implementation of the o.a.g.security.SecurityManager interface.

spring-data-geode-test/src/main/java/org/springframework/data/gemfire/tests/objects/geode/security/TestSecurityManager.java

@@ -0,0 +1,53 @@
+/*
+ *  Copyright 2018 the original author or authors.
+ *
+ *  Licensed 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 org.springframework.data.gemfire.tests.objects.geode.security;
+
+import static org.springframework.data.gemfire.util.RuntimeExceptionFactory.newIllegalStateException;
+
+import java.util.Optional;
+import java.util.Properties;
+import java.util.concurrent.atomic.AtomicReference;
+
+import org.apache.geode.security.AuthenticationFailedException;
+
+/**
+ * Test {@link org.apache.geode.security.SecurityManager} implementation used for testing purposes (only).
+ *
+ * @author John Blum
+ * @see java.util.Properties
+ * @see org.apache.geode.security.SecurityManager
+ * @since 1.0.0
+ */
+@SuppressWarnings("unused")
+public class TestSecurityManager implements org.apache.geode.security.SecurityManager {
+
+	private static final AtomicReference<TestSecurityManager> instance = new AtomicReference<>(null);
+
+	public static TestSecurityManager getInstance() {
+
+		return Optional.ofNullable(instance.get())
+			.orElseThrow(() -> newIllegalStateException("No TestSecurityManager was initialized"));
+	}
+
+	public TestSecurityManager() {
+		instance.compareAndSet(null, this);
+	}
+
+	@Override
+	public Object authenticate(Properties credentials) throws AuthenticationFailedException {
+		throw new UnsupportedOperationException("Not Implemented");
+	}
+}