undefined method `required_args' when running `rake run`

Reproduce the failure with rake run[fib.rb] and begin at src/main/ruby/ruby_flux/body_compiler.rb:29, following the calls through method_compiler.rb, class_compiler.rb, and compiler.rb. Done means the Fibonacci example runs without the required_args NoMethodError.

When I run rake run[fib.rb], it failed with the following information: NoMethodError: undefined method `required_args' for #Java::OrgJrubyParser::StaticScope:0x37271612
Here is detailed:

➜  rubyflux git:(master) ✗ pwd
/home/justme0/programs/rubyflux
➜  rubyflux git:(master) ✗ ls
dependency-reduced-pom.xml  fib.rb  LICENSE  pom.xml  Rakefile  README.md  src/  target/
➜  rubyflux git:(master) ✗ cat fib.rb
def fib(a)
  if a < 2
    a
  else
    fib(a - 1) + fib(a - 2)
  end
end

puts fib(40)
➜  rubyflux git:(master) ✗ echo $PATH 
/home/justme0/Downloads/jruby-9.1.2.0/bin /usr/local/sbin /usr/local/bin /usr/sbin /usr/bin /sbin /bin /usr/games /usr/local/games
➜  rubyflux git:(master) ✗ mvn --version
Apache Maven 3.0.5
Maven home: /usr/share/maven
Java version: 1.8.0_45-internal, vendor: Oracle Corporation
Java home: /usr/lib/jvm/java-8-openjdk-amd64/jre
Default locale: en_US, platform encoding: UTF-8
OS name: "linux", version: "3.19.0-59-generic", arch: "amd64", family: "unix"
➜  rubyflux git:(master) ✗ jruby --version
jruby 9.1.2.0 (2.3.0) 2016-05-26 7357c8f OpenJDK 64-Bit Server VM 25.45-b02 on 1.8.0_45-internal-b14 +jit [linux-x86_64]
➜  rubyflux git:(master) ✗ ruby --version
ruby 2.2.4p230 (2015-12-16 revision 53155) [x86_64-linux]
➜  rubyflux git:(master) ✗ rake --version
rake, version 10.4.2
➜  rubyflux git:(master) ✗ echo $SHELL 
/usr/bin/fish
➜  rubyflux git:(master) ✗ rake run[fib.rb]
jruby -I target:src/main/ruby src/main/ruby/ruby_flux.rb fib.rb
NoMethodError: undefined method `required_args' for #<Java::OrgJrubyParser::StaticScope:0x37271612>
             start at /home/justme0/programs/rubyflux/src/main/ruby/ruby_flux/body_compiler.rb:29
             start at /home/justme0/programs/rubyflux/src/main/ruby/ruby_flux/method_compiler.rb:53
             start at /home/justme0/programs/rubyflux/src/main/ruby/ruby_flux/class_compiler.rb:41
  block in compile at /home/justme0/programs/rubyflux/src/main/ruby/ruby_flux/compiler.rb:27
              each at org/jruby/RubyArray.java:1593
           compile at /home/justme0/programs/rubyflux/src/main/ruby/ruby_flux/compiler.rb:19
             <top> at src/main/ruby/ruby_flux.rb:45
rake aborted!
Command failed with status (1): [jruby -I target:src/main/ruby src/main/rub...]
/home/justme0/programs/rubyflux/Rakefile:24:in `block in (root)'
Tasks: TOP => run => compile => generate
(See full trace by running task with --trace)

I guess it is about arguments. Thank you very much!