MavenJobWithDetails behaves different than JobWithDetails for methods

[khmarbaise]

In MavenJobWithDetails those methods return null instead of MavenBuild.BUILD_HAS_NEVER_RAN in accordance with JobWithDetails methods which return Build.BUILD_HAS_NEVER_RAN.

 public MavenBuild getLastBuild();
 public MavenBuild getLastCompletedBuild();
 public MavenBuild getLastFailedBuild();
 public MavenBuild getLastStableBuild();
 public MavenBuild getLastSuccessfulBuild();
 public MavenBuild getLastUnstableBuild();
 public MavenBuild getLastUnsuccessfulBuild();