Fix eclipse build. (#28236)

Relates #28191

Author: jpountz

libs/elasticsearch-core/src/main/eclipse-build.gradle

@@ -0,0 +1,2 @@
+// this is just shell gradle file for eclipse to have separate projects for elasticsearch-core src and tests
+apply from: '../../build.gradle'

libs/elasticsearch-core/src/test/eclipse-build.gradle

@@ -0,0 +1,6 @@
+// this is just shell gradle file for eclipse to have separate projects for elasticsearch-core src and tests
+apply from: '../../build.gradle'
+
+dependencies {
+  testCompile project(':libs:elasticsearch-core')
+}

settings.gradle

@@ -108,6 +108,7 @@ if (isEclipse) {
   // eclipse cannot handle an intermediate dependency between main and test, so we must create separate projects
   // for server-src and server-tests
   projects << 'server-tests'
+  projects << 'libs:elasticsearch-core-tests'
 }
 
 include projects.toArray(new String[0])
@@ -125,6 +126,10 @@ if (isEclipse) {
   project(":server").buildFileName = 'eclipse-build.gradle'
   project(":server-tests").projectDir = new File(rootProject.projectDir, 'server/src/test')
   project(":server-tests").buildFileName = 'eclipse-build.gradle'
+  project(":libs:elasticsearch-core").projectDir = new File(rootProject.projectDir, 'libs/elasticsearch-core/src/main')
+  project(":libs:elasticsearch-core").buildFileName = 'eclipse-build.gradle'
+  project(":libs:elasticsearch-core-tests").projectDir = new File(rootProject.projectDir, 'libs/elasticsearch-core/src/test')
+  project(":libs:elasticsearch-core-tests").buildFileName = 'eclipse-build.gradle'
 }
 
 /**