Revert "[build] removed obsolete monkey patches"

This reverts commit 30dad24.

lib/pom.rb

@@ -34,6 +34,23 @@ def version
 
 project 'JRuby Lib Setup' do
 
+  # TODO move those to method to ruby-maven
+  class ::Java::JavaIo::File
+    def to_pathname
+      to_s.gsub( /\\/, '/' )
+    end
+  end
+  class ::Java::JavaLang::String
+    def to_pathname
+      to_s.gsub( /\\/, '/' )
+    end
+  end
+  class ::String
+    def to_pathname
+      self.gsub( /\\/, '/' )
+    end
+  end
+
   version = File.read( File.join( basedir, '..', 'VERSION' ) ).strip
 
   model_version '4.0.0'