only enable gradle menu when the gradle nature is present

[a1dutch]

undoes the commented out filter to only display the gradle menu when the nature has been added.

[paulvi]

BTW @spring-project was there plan to enable some Gradle functionality, when project is without Gradle feature?

[BoykoAlex]

The change looks good to me.
I'd follow the M2E tooling and enable/disable Gradle features similar to the ones in M2E.
Maven menu is not available for projects without Maven nature, consequently i'd do the same for Gradle.

[paulvi]

When developer considers migrating from Maven to Gradle, it would be help for him to launch both builds, compare dependencies etc...

[a1dutch]

It's possible to have both maven and gradle natures on the same project

[a1dutch]

Will this be in the nightly build tonight?

[BoykoAlex]

I have merged your PR, but in order to do so, I had to ask you to sign the CLA first (Contributor License Agreement). Is there any chance you've signed the CLA?
You can sign it here: https://support.springsource.com/spring_eclipsecla_committer_signup

[a1dutch]

just done it