[m2e-users] Build problems after upgrading to Eclipse 4.5

[Emond Papegaaij <emond.papegaaij@xxxxxxxxxx>]

Hi,

For the past year, we've been monitoring progress on Eclipse 4.5 (and now 4.6) 
to determine a good moment for a company-wide upgrade from 4.4.2 to a new 
version of Eclipse. However, a regression in m2e is holding us back at the 
moment: projects often show as 'not up-to-date' and require a rebuild.

These are the actions I've taken to reproduce this problem:
 - create a new workspace and clone several projects from git (on the cmdline)
 - import existing maven projects (selecting the workspace root to import all 
projects at once: 214 maven modules over 6 projects with 3M lines of Java 
code)
 - wait until the build is finished

After this, 26 of the 214 projects have the m2e 'project is not up-to-date' 
error marker, instructing me to update the Maven projects. This happens in 
Eclipse 4.5.2 and 4.6M6, but not in 4.4.2. The projects involved seem to be 
the same every time, but so far, I've not been able to find a relation between 
these projects. Updating the projects fixes the error, but new markers are 
likely to appear. They seem to appear much more often than in 4.4.

As we would really like to see this problem fixed in a later version of m2e, 
but have no idea what's causing it, can someone here help me with diagnosing 
this issue? Is there a way to find why m2e marks these projects as 'not up-to-
date'? How can a project become 'not up-to-date' directly after importing it?

Best regards,
Emond Papegaaij