Package dbus-java appears to be using Java generics, but generates class files in format older than 49.0, which corresponds to J2SE 5.0, in which generics were introduced. Please update this package to generate classes in format 49.0 or above. This corresponds to -target 1.5 option of javac (or ecj). For more information, see bug #842394
dbus-java is indeed using generics. But all the classfiles it creates out of java files have a class file format of 51.0. The build scripts do not specify a -target paramter at all. The only class file that have a different version are those that are generated by msgfmt --java2. Closing as NOTABUG.