Jasper Reports: how to add own Functions to Expression Editor - jasper-reports

Question

I am using Jaspersoft Studio 6.6 and try to add own functions to the Expression Editor.
Therefore i follow the tutorial Jaspersoft Studio Expression Editor: how to extend it and contribute your own functions (part 2) - updated for version 5.5 (i was not able to find a more current version so i guess this one should be still correct)
All works fine but i had to replace the language of the generated report (SampleFunctionsReport.jrxml) from groovy to java to get rid of class not found exceptions
Finally the following Errors are remaining:
Description Resource Path Location Type
The method HELLO_WORLD_MSG() is undefined for the type SampleFunctions_1541665022158_603382 SampleFunctionsReport.jrxml /MyFunctions line 37 JRXML Problem
The method HELLO_WORLD_MSG() is undefined for the type SampleFunctions_1541665022158_603382 value = HELLO_WORLD_MSG( ); SampleFunctionsReport.jrxml /MyFunctions line 0 JRXML Problem
The method REPEAT_MSG(String, int, boolean) is undefined for the type SampleFunctions_1541665022158_603382 SampleFunctionsReport.jrxml /MyFunctions line 52 JRXML Problem
The method REPEAT_MSG(String, int, boolean) is undefined for the type SampleFunctions_1541665022158_603382 value = REPEAT_MSG("A message that will be probably repeated",5,true); SampleFunctionsReport.jrxml /MyFunctions line 0 JRXML Problem
I checked the points of the tutorial a couple of times...
can someone reproduce my problem?
What am i missing?

Answer 1

<import value="test.customfunctions.*"/>
this is the code from my jrxml, which is fine.
when i tried to enter the full class name - i got an error, that the package cannot be added.
today i tried the same again - and its working. even the resulting XML is identical!