Use Java SDK defined on JAVA_HOME by default on JetBrains IDEs

Author: felladrin

components/ide/jetbrains/backend-plugin/src/main/kotlin/io/gitpod/jetbrains/remote/GitpodProjectManager.kt

@@ -10,8 +10,10 @@ import com.intellij.openapi.module.Module
 import com.intellij.openapi.module.ModuleManager
 import com.intellij.openapi.project.ModuleListener
 import com.intellij.openapi.project.Project
+import com.intellij.openapi.projectRoots.JdkUtil
 import com.intellij.openapi.projectRoots.ProjectJdkTable
 import com.intellij.openapi.projectRoots.Sdk
+import com.intellij.openapi.projectRoots.SimpleJavaSdkType
 import com.intellij.openapi.roots.ModuleRootModificationUtil
 import com.intellij.openapi.roots.ProjectRootManager
 import com.intellij.util.application
@@ -40,8 +42,16 @@ class GitpodProjectManager(
         application.invokeLaterOnWriteThread {
             application.runWriteAction {
                 try {
-                    ProjectJdkTable.getInstance().preconfigure()
-                    pendingSdk.complete(ProjectJdkTable.getInstance().allJdks.firstOrNull())
+                    val jdkTable = ProjectJdkTable.getInstance()
+                    val javaHome = System.getenv("JAVA_HOME")
+                    if (javaHome !== null && JdkUtil.checkForJdk(javaHome)) {
+                        val sdk = SimpleJavaSdkType.getInstance().createJdk("Default", javaHome)
+                        jdkTable.addJdk(sdk)
+                        pendingSdk.complete(sdk)
+                    } else {
+                        jdkTable.preconfigure()
+                        pendingSdk.complete(jdkTable.allJdks.firstOrNull())
+                    }
                 } catch (t: Throwable) {
                     pendingSdk.completeExceptionally(t)
                 }
@@ -78,4 +88,4 @@ class GitpodProjectManager(
             }
         }
     }
-}
+}