Unexpected output "*** PatternParameterImpl" in the java console

We have an unexpected output "*** PatternParameterImpl" in our java console.

Do you know why?

Caused by:

PrintStream.write(String) line: 603    
PrintStream.print(String) line: 745    
PrintStream.println(String) line: 882    
ThreadPrintStream.println(String) line: 179    
TYS.k() line: 199    
TYM.Z(boolean, String, OType, Object) line: 546    
TYM.<init>(TSR, ClassLoader, SCM, PersistenceUnitInfo, String, ERR, boolean) line: 196    
EMF(OMF).w(STO, ClassLoader) line: 866    
EMF(OMF).s(String, String) line: 818    
EMF.s(String, String) line: 130    
EMF(OMF).x(String, String) line: 716    
EMF.createEntityManager() line: 149    

Thank you for this report. It was a debugging message in build 2.8.7_03 that was later removed in build 2.8.7_04. You can either ignore this message or upgrade to 2.8.7_04.