Add static destroy() method to destroy the Singleton TestProperties instance.

spring-data-geode-test/src/main/java/org/springframework/data/gemfire/tests/config/TestProperties.java

@@ -70,6 +70,15 @@ public class TestProperties implements Iterable<String> {
 		return testPropertiesReference;
 	}
 
+	/**
+	 * Destroys the managed {@literal Singleton} {@link TestProperties} instance.
+	 */
+	public static void destroy() {
+		testPropertiesReference.clearSystemProperties();
+		testPropertiesReference.clear();
+		testPropertiesReference = null;
+	}
+
 	private final Properties testProperties;
 
 	/**

spring-data-geode-test/src/test/java/org/springframework/data/gemfire/tests/config/TestPropertiesIntegrationTests.java

@@ -69,6 +69,23 @@ public class TestPropertiesIntegrationTests {
 		assertThat(properties).isSameAs(TestProperties.getInstance());
 	}
 
+	@Test
+	public void destroySingleTestPropertiesInstance() {
+
+		TestProperties testProperties = TestProperties.getInstance()
+			.set("port", "12345");
+
+		assertThat(testProperties).isNotNull();
+		assertThat(testProperties.get("port")).isEqualTo("12345");
+
+		TestProperties.destroy();
+
+		TestProperties newTestProperties = TestProperties.getInstance();
+
+		assertThat(newTestProperties).isNotSameAs(testProperties);
+		assertThat(newTestProperties).isEmpty();
+	}
+
 	@Test
 	public void getTestPropertiesResourceIsCorrect() {