Use Eclipse m2e 1.14.0

Update our Oomph setup to use m2e 1.14.0 from their milestone
update site. Unfortunately we need to use the milestone since
the fix for https://bugs.eclipse.org/bugs/show_bug.cgi?id=548652
has not yet made it into a stable m2e release.

Closes gh-19280

CONTRIBUTING.adoc

@@ -142,6 +142,10 @@ You can import the Spring Boot code into any Eclipse 2019-09-based distribution.
 easiest way to setup a new environment is to use the Eclipse Installer with the provided
 `spring-boot-project.setup` file (in the `/eclipse` folder).
 
+NOTE: Due to m2e issue https://bugs.eclipse.org/bugs/show_bug.cgi?id=548652[#548652] you need to be running m2e 1.14.0 or higher.
+An early milestone is available from http://download.eclipse.org/technology/m2e/milestones/1.14/.
+
+
 
 ==== Using the Eclipse Installer
 Spring Boot includes a `.setup` files which can be used with the Eclipse Installer to

eclipse/spring-boot-project.setup

@@ -69,7 +69,7 @@
     <requirement
         name="org.eclipse.jst.web_ui.feature.feature.group"/>
     <requirement
-        name="org.eclipse.m2e.feature.feature.group"/>
+        name="org.eclipse.m2e.feature.feature.group" versionRange="[1.14.0,2.0.0)"/>
     <requirement
         name="org.eclipse.oomph.setup.maven.feature.group"/>
      <requirement
@@ -86,6 +86,8 @@
           name="org.springframework.ide.eclipse.boot.dash.feature.feature.group"/>
     <requirement
           name="org.springframework.tooling.boot.ls.feature.feature.group"/>
+    <repository
+          url="http://download.eclipse.org/technology/m2e/milestones/1.14/"/>
     <repository
         url="https://dl.bintray.com/spring/javaformat-eclipse/"/>
     <repository