Add optional 'ch.qos.logback.logback-classic' dependency.

spring-data-geode-test/build.gradle

@@ -11,6 +11,7 @@ dependencies {
 	compile "org.projectlombok:lombok"
 	compile "org.springframework:spring-test"
 	compile "org.springframework.data:spring-data-geode"
+	optional "ch.qos.logback:logback-classic"
 
 	provided ("org.springframework.boot:spring-boot-starter") {
 		exclude group: "org.springframework.boot", module: "spring-boot-starter-logging";

spring-data-geode-test/pom.xml

@@ -83,6 +83,12 @@
 			<artifactId>spring-data-geode</artifactId>
 		</dependency>
 
+		<dependency>
+			<groupId>ch.qos.logback</groupId>
+			<artifactId>logback-classic</artifactId>
+			<optional>true</optional>
+		</dependency>
+
 	</dependencies>
 
 </project>