Gradle:

- default is now Java 8 toolchain (to fix Eclipse project import)
- `src/main/module-info` and `src/main/java9` are compiled with Java 11 toolchain (if global toolchain is Java 8)
- `src/main/module-info` and `src/main/java9` are no longer imported into Eclipse projects
- task `errorprone` now uses at least Java 11 toolchain

buildSrc/src/main/kotlin/flatlaf-toolchain.gradle.kts

@@ -18,6 +18,8 @@ plugins {
 	java
 }
 
+val toolchainJavaVersion: String by rootProject.extra
+
 java.toolchain {
-	languageVersion = JavaLanguageVersion.of( System.getProperty( "toolchain", "11" ) )
+	languageVersion = JavaLanguageVersion.of( toolchainJavaVersion )
 }