Add optional Querydsl dependency.

Closes #3107

Author: mp911de

pom.xml

@@ -144,6 +144,13 @@
 			</exclusions>
 		</dependency>
 
+		<dependency>
+			<groupId>com.querydsl</groupId>
+			<artifactId>querydsl-core</artifactId>
+			<version>${querydsl}</version>
+			<optional>true</optional>
+		</dependency>
+
 		<!-- Jackson JSON Mapper -->
 		<dependency>
 			<groupId>com.fasterxml.jackson.core</groupId>