do not clear the uriResourceMap in the builder

see https://www.eclipse.org/forums/index.php/m/1461124/#msg_1461124

Change-Id: I07987a20a3d2c8a1d99aea974f6aa3a473e18a0b
[releng] org.eclipse.xtext should have require-bundle to
com.google.inject as mandatory Bug 439758

Change-Id: Id87bdd4239ea0acdf202e8b32d062c804d4b83f6
Merge "[releng] org.eclipse.xtext should have require-bundle to com.google.inject as mandatory Bug 439758"
Merge "do not clear the uriResourceMap in the builder"