I have n number of plugins in my RCP product where they are dependent on each other. Is it a good practice to specify their version or without version number while importing them in dependencies as Required plugins.
P.S. : If I specify version number, whenever my plug-in version change, I should change each and every plugin where I have added them as dependency.
No, you don't have to specify a version. In this case any version will do.
If you specify a single version then that is the minimum version required - an exact match is not required.
Finally you can specify a range of values - this gives a minimum and maximum version that is allowed.
If you know that a plug-in requires at least a minimum version of another plug-in you should specify that minimum version. You only need to change the minimum version when you make incompatible changes.
You might specify a maximum version of you think you will be making incompatible changes in future versions.