Splits nio project into two for eclipse build only (#27939)

* Splits nio project into two for eclipse build only

https://github.com/elastic/elasticsearch/pull/27801 introduced a new gradle project `:libs:elasticsearch-nio` which creates cyclical project dependencies when importingthe projects into Eclipse.

This change applies the same trick as we have for the core project where, and building for Eclipse, splits the `:libs:elasticsearch-nio` project into `:libs:elasticsearch-nio` which points to `src/main` and `:libs:elasticsearch-nio-tests` which points to `src/test`. This prevents cyclical project dependencies in Eclipse arising from the fact that eclipse does not separate compile/runtime dependencies from test dependencies.

* Removes integTest bits since there are none

libs/elasticsearch-nio/build.gradle

@@ -39,8 +39,24 @@ dependencies {
   testCompile "com.carrotsearch.randomizedtesting:randomizedtesting-runner:${versions.randomizedrunner}"
   testCompile "junit:junit:${versions.junit}"
   testCompile "org.hamcrest:hamcrest-all:${versions.hamcrest}"
-  testCompile("org.elasticsearch.test:framework:${version}") {
-    exclude group: 'org.elasticsearch', module: 'elasticsearch-nio'
+  
+  if (isEclipse == false || project.path == ":libs:elasticsearch-nio-tests") {
+      testCompile("org.elasticsearch.test:framework:${version}") {
+        exclude group: 'org.elasticsearch', module: 'elasticsearch-nio'
+      }
+  }
+}
+
+if (isEclipse) {
+  // in eclipse the project is under a fake root, we need to change around the source sets
+  sourceSets {
+    if (project.path == ":libs:elasticsearch-nio") {
+      main.java.srcDirs = ['java']
+      main.resources.srcDirs = ['resources']
+    } else {
+      test.java.srcDirs = ['java']
+      test.resources.srcDirs = ['resources']
+    }
   }
 }
 

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

@@ -0,0 +1,3 @@
+
+// this is just shell gradle file for eclipse to have separate projects for elasticsearch-nio src and tests
+apply from: '../../build.gradle'

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

@@ -0,0 +1,7 @@
+
+// this is just shell gradle file for eclipse to have separate projects for elasticsearch-nio src and tests
+apply from: '../../build.gradle'
+
+dependencies {
+  testCompile project(':libs:elasticsearch-nio')
+}

settings.gradle

@@ -109,6 +109,7 @@ if (isEclipse) {
   // eclipse cannot handle an intermediate dependency between main and test, so we must create separate projects
   // for core-src and core-tests
   projects << 'core-tests'
+  projects << 'libs:elasticsearch-nio-tests'
 }
 
 include projects.toArray(new String[0])
@@ -131,6 +132,10 @@ if (isEclipse) {
   project(":core").buildFileName = 'eclipse-build.gradle'
   project(":core-tests").projectDir = new File(rootProject.projectDir, 'core/src/test')
   project(":core-tests").buildFileName = 'eclipse-build.gradle'
+  project(":libs:elasticsearch-nio").projectDir = new File(rootProject.projectDir, 'libs/elasticsearch-nio/src/main')
+  project(":libs:elasticsearch-nio").buildFileName = 'eclipse-build.gradle'
+  project(":libs:elasticsearch-nio-tests").projectDir = new File(rootProject.projectDir, 'libs/elasticsearch-nio/src/test')
+  project(":libs:elasticsearch-nio-tests").buildFileName = 'eclipse-build.gradle'
 }
 
 /**