It seems that in JavaFX there is no requirement for the declared package name to match the source file physical location.
The result is that the source file is in such a case marked with error but the project compiles and runs just fine.
I will attach a sample project showing this problem.
Created attachment 89610 [details]
The solution would be not to use WrongPackageStatmentTask at all.
fixed in http://hg.netbeans.org/javafx/rev/d764ced04d66
It is fixed but it cause that the useful hints also are not shown.
See issue 177187
Since it is not possible to have both #174734 and #177187 fixed at the same time (as the requirements are contradictory) I am reverting the fix for this issue and restoring the old behavior (thus fixing #177817).