It is not clear what version you have (es2 pack?) but there were definite problems with the workspace source code and customization in the ES2 GM release.  These were fixed in SP1 and are also in SP2.

Note that the workspace source is distributed in both the LC and Workbench installs but the Workbench install may contain the original GM release source, depending on the Workbench version you have.  Workbench 9.5 was released with LC ES 2.5 (aka SP2), but i'm not sure if that even has the updated source.

To avoid any confusion, you should only use the source from the LC ES2 install.  And to get the latest workspace source you should apply the latest service pack (this would be SP2 at this time) and get the latest ProcessManagement Patch for SP2.  The workspace source is in the zip file at the location indicated in Jasmine's reply.

I'm unaware of any way to get the code other than applying the SP (1 or 2) and then applying the latest Process Management QuickFix for the SP you choose.  My opinion is that keeping as current as safely possible is best if you want to benefit from all fixes so I would go with SP2.  SP2 has been out for quite a while so I consider it a safe choice.   The SP2 workbench introduced some new features but fully supports any existing applications so this shouldn't be a problem.  Whatever you choose, testing with your environment is always advised, but I'm sure you would do this anyway,

Also note that updated workspace source could depend on changes in the server code so taking a newer workspace source and running it against an older version of the server may have problems.  So whatever source you get, you should make sure the server is at least as current.

Jon