Fixed jdk version for javadoc and OSGi

Author: thboileau

build/build.properties

@@ -12,8 +12,8 @@ meta.release-type: snapshot
 version-minor: ${major-number}.${minor-number}
 
 # Version of JDK required
-jdk.compilation.version: 1.8
-bundle.required-execution-environment: JavaSE-1.8
+jdk.compilation.version: 11
+bundle.required-execution-environment: JavaSE-11
 
 # The base directory where a Restlet distributions is zipped
 # Each Restlet version will create its own file