In JRuby 9.1.14.0 (and current master), the following command prints nil, whereas for MRI it prints a large S-expression.

ruby -rripper -e "p Ripper.sexp('class C; private def m; a.e do; end; end; end')"

If I remove private or a. the same S-expression is returned from MRI and JRuby. If I change the block to use { ... } or add paranthesis around the def m; ...; end it also works.

Loading the code into JRuby works just fine, but parsing it with Ripper does not.

This seems related to the issue #4663, but the syntax is just slightly different.