diff --git a/lib/ruby/site_ruby/shared/jruby/core_ext/method.rb b/lib/ruby/site_ruby/shared/jruby/core_ext/method.rb
new file mode 100644
index 00000000000..e5d4903ca34
--- /dev/null
+++ b/lib/ruby/site_ruby/shared/jruby/core_ext/method.rb
@@ -0,0 +1,73 @@
+require 'jruby'
+
+class Method
+  def parameters
+    self_r = JRuby.reference0(self)
+    method = self_r.get_method
+    args_ary = []
+
+    case method
+    when MethodArgs2
+      return RuntimeHelpers.parameter_list_to_parameters(JRuby.runtime, method.parameter_list, true)
+    when MethodArgs
+      args_node = method.args_node
+
+      # "pre" required args
+      required_pre = args_node.pre
+      if required_pre
+        for req_pre_arg in required_pre.child_nodes
+          if req_pre_arg.kind_of? MultipleAsgn19Node
+            args_ary << [:req]
+          else
+            args_ary << [:req, req_pre_arg ? req_pre_arg.name.intern : nil]
+          end
+        end
+      end
+
+      # optional args in middle
+      optional = args_node.opt_args
+      if optional
+        for opt_arg in optional.child_nodes
+          args_ary << [:opt, opt_arg ? opt_arg.name.intern : nil]
+        end
+      end
+
+      # rest arg
+      if args_node.rest_arg >= 0
+        rest = args_node.rest_arg_node
+
+        if rest.kind_of? UnnamedRestArgNode
+          if rest.star?
+            args_ary << [:rest]
+          end
+        else
+          args_ary << [:rest, rest ? rest.name.intern : nil]
+        end
+      end
+
+      # "post" required args
+      required_post = args_node.post
+      if required_post
+        for req_post_arg in required_post.child_nodes
+          if req_post_arg.kind_of? MultipleAsgn19Node
+            args_ary << [:req]
+          else
+            args_ary << [:req, req_post_arg ? req_post_arg.name.intern : nil]
+          end
+        end
+      end
+
+      # block arg
+      block = args_node.block
+      if block
+        args_ary << [:block, block.name.intern]
+      end
+    else
+      if method.arity == Arity::OPTIONAL
+        args_ary << [:rest]
+      end
+    end
+
+    args_ary
+  end
+end
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