Issue Description:

Jaspersoft Studio v7.5.0, at the final step of installing additional community/commercial/customer created plug-ins in Studio, the installation failed with the following entries in the installation window: 

 Cannot complete the install because one or more required items could not be found.

  Software being installed: Test2 1.0.0.202007171002 (com.xxx.test2.feature.group 1.0.0.202007171002)
  Missing requirement: Test 1.0.0.202007171002 (com.xxx.test 1.0.0.202007171002) requires 'osgi.ee; (&(osgi.ee=JavaSE)(version=1.8))' 
  but it could not be found
  Cannot satisfy dependency:
    From: Test2 1.0.0.202007171002 (com.xxx.test2.feature.group 1.0.0.202007171002)
    To: org.eclipse.equinox.p2.iu; com.xxx.test [1.0.0.202007171002,1.0.0.202007171002]

Resolution:

When installing additional community/commercial/customer created plugins, we need to add two items from Eclipse repository as below:

• Into the installation dialog click on the "Manage" button. It will take you to the preference page where you can play with the update sites available.
• You should see only the "local" plug-in file you added when trying to install the customer plugin
• Proceed in adding the following two

     a) Eclipse Repository - http://download.eclipse.org/releases/2019-06 

     b) The Eclipse Project repository - http://download.eclipse.org/eclipse/updates/4.12 

NOTE: we need these specific two because JSS 7.5.0 PRO is built on an Eclipse 4.12 platform. 

(A fixed pending in the next Jaspersoft Studio release. Internal reference number #JSS-2881).