The Plugin seems to use Java 1.6 Methods

FATAL: java.lang.String.isEmpty()Z
java.lang.NoSuchMethodError: java.lang.String.isEmpty()Z
at hudson.plugins.emma.EmmaPublisher.perform(EmmaPublisher.java:105)
at hudson.tasks.BuildStepMonitor$3.perform(BuildStepMonitor.java:36)
at hudson.model.AbstractBuild$AbstractRunner.perform(AbstractBuild.java:582)
at hudson.model.AbstractBuild$AbstractRunner.performAllBuildStep(AbstractBuild.java:563)
at hudson.model.AbstractBuild$AbstractRunner.performAllBuildStep(AbstractBuild.java:550)
at hudson.model.Build$RunnerImpl.post2(Build.java:152)
at hudson.model.AbstractBuild$AbstractRunner.post(AbstractBuild.java:528)
at hudson.model.Run.run(Run.java:1221)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:46)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:122)

Not sure whether this should be considered a bug but it prevents our Hudson from successfull building and others have the same problem:
http://wiki.jenkins-ci.org/display/JENKINS/Emma+Plugin?focusedCommentId=42469455#comment-42469455