missed java version updates

Author: holgerfriedrich

examples/karaf-graphql-example/karaf-graphql-example-websocket/pom.xml

@@ -70,8 +70,8 @@
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
                 <configuration>
-                    <source>11</source>
-                    <target>11</target>
+                    <source>21</source>
+                    <target>21</target>
                 </configuration>
             </plugin>
             <plugin>