@Kai Had to re-install my dev env today, and with a clean slate I run into this:
Executing bootstrap tasks
Java™ SE Runtime Environment 1.8.0_121-b13
Product org.eclipse.products.epp.package.java.neon
Workspace /Users/kgoderis/openHAB/openhab2-master2/ws
Project com.github.openhab2.1_infra.master
Project com.github.openhab2.2_openhab2.master
Project com.github.openhab2.4_esh.master
Project com.github.openhab2.5_core.master
Bundle org.eclipse.oomph.setup 1.8.0.v20170408-0745, build=3098, branch=e12ba4db800d8f30e47fd2525429e2f55baf9396
Bundle org.eclipse.oomph.setup.core 1.8.0.v20170531-0903, build=3098, branch=e12ba4db800d8f30e47fd2525429e2f55baf9396
Bundle org.eclipse.oomph.setup.installer 1.9.0.v20170706-0615, build=3098, branch=e12ba4db800d8f30e47fd2525429e2f55baf9396
Bundle org.eclipse.oomph.setup.p2 1.8.0.v20170318-0419, build=3098, branch=e12ba4db800d8f30e47fd2525429e2f55baf9396
Performing Workspace /Users/kgoderis/openHAB/openhab2-master2/ws
Performing P2 Director (Eclipse IDE for Java Developers (Neon))
Offline = false
Mirrors = true
Resolving 32 requirements from 5 repositories to /Users/kgoderis/openHAB/openhab2-master2/Eclipse.app/Contents/Eclipse
Requirement org.eclipse.wst.xml_ui.feature.feature.group
Requirement org.eclipse.mylyn.java_feature.feature.group
Requirement org.codehaus.groovy.eclipse.feature.feature.group
Requirement org.eclipse.mylyn.git.feature.group
Requirement org.eclipse.pde.feature.group
Requirement org.eclipse.wst.jsdt.feature.feature.group
Requirement org.eclipse.wst.web_ui.feature.feature.group
Requirement epp.package.java [4.6.0,4.7.0)
Requirement org.eclipse.platform.feature.group [4.6.0,4.7.0)
Requirement org.eclipse.rcp.feature.group [4.6.0,4.7.0)
Requirement org.eclipse.buildship.feature.group
Requirement org.eclipse.egit.feature.group
Requirement org.eclipse.egit.mylyn.feature.group
Requirement org.eclipse.jdt.feature.group
Requirement org.eclipse.jgit.feature.group
Requirement org.eclipse.m2e.feature.feature.group
Requirement org.eclipse.m2e.logback.feature.feature.group
Requirement org.eclipse.mylyn.bugzilla_feature.feature.group
Requirement org.eclipse.mylyn.context_feature.feature.group
Requirement org.eclipse.mylyn.hudson.feature.group
Requirement org.eclipse.mylyn.ide_feature.feature.group
Requirement org.eclipse.mylyn.wikitext_feature.feature.group
Requirement org.eclipse.mylyn_feature.feature.group
Requirement org.eclipse.recommenders.mylyn.rcp.feature.feature.group
Requirement org.eclipse.recommenders.rcp.feature.feature.group
Requirement org.eclipse.recommenders.snipmatch.rcp.feature.feature.group
Requirement org.eclipse.oomph.setup.feature.group
Requirement org.eclipse.oomph.setup.jdt.feature.group
Requirement org.eclipse.oomph.setup.git.feature.group
Requirement org.eclipse.oomph.setup.workingsets.feature.group
Requirement org.eclipse.oomph.setup.projects.feature.group
Requirement org.eclipse.oomph.setup.pde.feature.group
Repository http://dist.springsource.org/snapshot/GRECLIPSE/e4.7/
Repository http://download.eclipse.org/technology/epp/packages/neon
Repository http://download.eclipse.org/releases/neon/201705151400
Repository http://download.eclipse.org/oomph/updates/milestone/latest
Repository http://download.eclipse.org/egit/updates
Adding repository http://download.eclipse.org/egit/updates
Adding repository http://download.eclipse.org/technology/epp/packages/neon
Adding repository http://download.eclipse.org/oomph/updates/milestone/latest
Adding repository http://dist.springsource.org/snapshot/GRECLIPSE/e4.7/
Adding repository http://download.eclipse.org/releases/neon/201705151400
Calculating requirements and dependencies.
Cannot complete the request. Generating details.
ERROR: org.eclipse.equinox.p2.director code=10053 Cannot complete the install because one or more required items could not be found.
at org.eclipse.oomph.util.OomphPlugin.coreException(OomphPlugin.java:280)
at org.eclipse.oomph.p2.internal.core.ProfileTransactionImpl.resolve(ProfileTransactionImpl.java:425)
at org.eclipse.oomph.p2.internal.core.ProfileTransactionImpl.commit(ProfileTransactionImpl.java:337)
at org.eclipse.oomph.setup.p2.impl.P2TaskImpl.perform(P2TaskImpl.java:729)
at org.eclipse.oomph.setup.internal.core.SetupTaskPerformer.doPerformNeededSetupTasks(SetupTaskPerformer.java:3324)
at org.eclipse.oomph.setup.internal.core.SetupTaskPerformer.performNeededSetupTasks(SetupTaskPerformer.java:3252)
at org.eclipse.oomph.setup.internal.core.SetupTaskPerformer.performTriggeredSetupTasks(SetupTaskPerformer.java:3233)
at org.eclipse.oomph.setup.internal.core.SetupTaskPerformer.perform(SetupTaskPerformer.java:3133)
at org.eclipse.oomph.setup.ui.wizards.ProgressPage$9.run(ProgressPage.java:567)
at org.eclipse.oomph.setup.ui.wizards.ProgressPage$11$1.run(ProgressPage.java:693)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:56)
ERROR: org.eclipse.equinox.p2.director code=0 Software being installed: artificial_root 1.0.0.v1508225478554
ERROR: org.eclipse.equinox.p2.director code=0 Missing requirement: Java Development Tools Core 3.13.50.xx-201710170420-e47 (org.eclipse.jdt.core 3.13.50.xx-201710170420-e47) requires ‘bundle org.eclipse.core.resources [3.12.0,4.0.0)’ but it could not be found
ERROR: org.eclipse.equinox.p2.director code=1 Cannot satisfy dependency:
ERROR: org.eclipse.equinox.p2.director code=0 From: artificial_root 1.0.0.v1508225478554
ERROR: org.eclipse.equinox.p2.director code=0 To: org.codehaus.groovy.eclipse.feature.feature.group 0.0.0
ERROR: org.eclipse.equinox.p2.director code=1 Cannot satisfy dependency:
ERROR: org.eclipse.equinox.p2.director code=0 From: artificial_root 1.0.0.v1508225478554
ERROR: org.eclipse.equinox.p2.director code=0 To: org.eclipse.jdt.feature.group 0.0.0
ERROR: org.eclipse.equinox.p2.director code=1 Cannot satisfy dependency:
ERROR: org.eclipse.equinox.p2.director code=0 From: Groovy-Eclipse Compilerless Feature 2.9.2.xx-201710170420-e47 (org.codehaus.groovy.compilerless.feature.feature.group 2.9.2.xx-201710170420-e47)
ERROR: org.eclipse.equinox.p2.director code=0 To: org.codehaus.groovy.headless.feature.feature.group [2.9.2.xx-201710170420-e47]
ERROR: org.eclipse.equinox.p2.director code=1 Cannot satisfy dependency:
ERROR: org.eclipse.equinox.p2.director code=0 From: Groovy-Eclipse Feature 2.9.2.xx-201710170420-e47 (org.codehaus.groovy.eclipse.feature.feature.group 2.9.2.xx-201710170420-e47)
ERROR: org.eclipse.equinox.p2.director code=0 To: org.codehaus.groovy.compilerless.feature.feature.group [2.9.2.xx-201710170420-e47]
ERROR: org.eclipse.equinox.p2.director code=1 Cannot satisfy dependency:
ERROR: org.eclipse.equinox.p2.director code=0 From: Groovy-Eclipse Headless Feature 2.9.2.xx-201710170420-e47 (org.codehaus.groovy.headless.feature.feature.group 2.9.2.xx-201710170420-e47)
ERROR: org.eclipse.equinox.p2.director code=0 To: org.codehaus.groovy.jdt.patch.feature.group [2.9.2.xx-201710170420-e47]
ERROR: org.eclipse.equinox.p2.director code=1 Cannot satisfy dependency:
ERROR: org.eclipse.equinox.p2.director code=0 From Patch: org.codehaus.groovy.jdt.patch.feature.group 2.9.2.xx-201710170420-e47 Eclipse Java Development Tools 3.12.3.v20170301-0400 (org.eclipse.jdt.feature.group 3.12.3.v20170301-0400)
ERROR: org.eclipse.equinox.p2.director code=0 To: org.eclipse.jdt.core [3.13.50.xx-201710170420-e47]
Took 2 seconds.
There are failed tasks.