Upgrade to Eclipse 2019.12

Closes gh-19281

CONTRIBUTING.adoc

@@ -138,13 +138,10 @@ can run this from the top-level directory:
 
 
 === Importing into Eclipse
-You can import the Spring Boot code into any Eclipse 2019-09-based distribution. The
+You can import the Spring Boot code into any Eclipse 2019-12-based distribution. The
 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 https://download.eclipse.org/technology/m2e/milestones/1.14/.
-
 
 
 ==== Using the Eclipse Installer
@@ -155,7 +152,7 @@ provision a new environment. To use the installer:
   https://www.eclipse.org/downloads/packages/installer[Eclipse Installer].
 * Switch to "Advanced Mode" using the drop down menu on the right.
 * Select "`Eclipse IDE for Java Developers`" under "`Eclipse.org`" as the product to
-  install, `2019-09` as the product version, and click "`next`".
+  install, `2019-12` as the product version, and click "`next`".
 * For the "`Project`" click on "`+`" to add a new setup file. Select "`Github Projects`"
   and browse for `<checkout>/eclipse/spring-boot-project.setup` from your locally cloned
   copy of the source code. Click "`OK`" to add the setup file to the list.

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" versionRange="[1.14.0,2.0.0)"/>
+        name="org.eclipse.m2e.feature.feature.group"/>
     <requirement
         name="org.eclipse.oomph.setup.maven.feature.group"/>
      <requirement
@@ -86,8 +86,6 @@
           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
@@ -131,14 +129,26 @@
     <workingSet
         name="spring-boot-starters">
       <predicate
+          xsi:type="predicates:OrPredicate">
+        <operand
             xsi:type="predicates:NamePredicate"
             pattern="spring-boot-starter(s|-.*)"/>
+        <operand
+            xsi:type="predicates:NamePredicate"
+            pattern="spring-boot-starter"/>
+      </predicate>
     </workingSet>
     <workingSet
         name="spring-boot-samples">
       <predicate
+          xsi:type="predicates:OrPredicate">
+        <operand
             xsi:type="predicates:NamePredicate"
             pattern="spring-boot-sample(s|-.*)"/>
+        <operand
+            xsi:type="predicates:NamePredicate"
+            pattern="spring-boot-samples-invoker"/>
+      </predicate>
     </workingSet>
     <workingSet
         name="spring-boot-tests">
@@ -225,7 +235,7 @@
     <setupTask
         xsi:type="setup:PreferenceTask"
         key="/instance/org.eclipse.m2e.core/eclipse.m2.hideFoldersOfNestedProjects"
-        value="false"/>
+        value="true"/>
     <setupTask
         xsi:type="setup:PreferenceTask"
         key="/instance/org.eclipse.m2e.core/eclipse.m2.updateIndexes"