plugin fails to build on 4-2-stable

[jbeal-work]

The plugin fails to compile against 4-2-stable

root@6b9449c40a68:/build# make package
[ 50%] Building CXX object CMakeFiles/irados.dir/irados/libirados.cpp.o
/irods_resource_plugin_rados/irados/libirados.cpp:1201:48: error: no member named 'is_dirty' in 'irods::physical_object'
                        bool is_dirty = ( itr->is_dirty() != 1 );
                                          ~~~  ^
1 error generated.
CMakeFiles/irados.dir/build.make:62: recipe for target 'CMakeFiles/irados.dir/irados/libirados.cpp.o' failed
make[2]: *** [CMakeFiles/irados.dir/irados/libirados.cpp.o] Error 1
CMakeFiles/Makefile2:67: recipe for target 'CMakeFiles/irados.dir/all' failed
make[1]: *** [CMakeFiles/irados.dir/all] Error 2
Makefile:151: recipe for target 'all' failed
make: *** [all] Error 2