Add static stopLogback() utility method to the LogbackSupport class.

spring-geode-project/spring-geode-starters/spring-geode-starter-logging/src/main/java/org/springframework/geode/logging/slf4j/logback/support/LogbackSupport.java

@@ -75,6 +75,16 @@ public abstract class LogbackSupport {
 		requireLoggerContext().putObject(SPRING_BOOT_LOGGING_SYSTEM_CLASS_NAME, new Object());
 	}
 
+	/**
+	 * Properly stops Logback classic.
+	 *
+	 * @see <a href="https://logback.qos.ch/manual/configuration.html#stopContext">Stopping logback-classic</a>
+	 */
+	public static void stopLogback() {
+		resolveLoggerContext()
+			.ifPresent(LoggerContext::stop);
+	}
+
 	/**
 	 * Resets the state of the SLF4J Logback logging provider and system.
 	 */