Facing issues with callback functions configuration

[Shiyaam Velan]

I am currently maintaining two appengine projects. To use the datastore callbacks (@PrePut) i have configured in eclipse as per the documentation in appengine (https://cloud.google.com/appengine/docs/java/datastore/callbacks#Using_Callbacks_With_Eclipse). When i deploy the projects I do not face any issues, but when someone else does (they have not configured in their machines) the PrePut function is not called. The appengine sdk used for these two projects point to my local machine. So the .factorypath in both projects points to my local machine folder. The weird thing is one project works fine and other one doesnt if someone else deploys. 

Is it necessary that everyone should configure the eclipse? If so how come one project works fine and the other doesnt. They do have the .factorypath, file in their system. Please help me out here.

[Nick (Cloud Platform Support)]

Could you elaborate a bit on what you mean by .factorypath in this context? Also what does it mean for "someone else (they have not configured their machine)" to notice that "PrePut function is not called" if you say that for "these two projects" (do you mean your project and the copy of the project for the other person?), the sdk "points to my local machine"? All of this needs clarification in my mind, and perhaps with some code as well, things will start to appear more clear.