Build: Allow running errorprone with Java 8

build.gradle.kts

@@ -224,6 +224,9 @@ allprojects {
             dependencies {
                 "errorprone"(libs.tools.errorprone.core)
                 "annotationProcessor"(libs.tools.errorprone.guava)
+                if (!JavaVersion.current().isJava9Compatible) {
+                    "errorproneJavac"(libs.tools.errorprone.javac)
+                }
             }
             tasks.withType<JavaCompile>().configureEach {
                 options.compilerArgs.addAll(listOf("-Xmaxerrs", "10000", "-Xmaxwarns", "10000", "-Werror"))

gradle/libs.versions.toml

@@ -13,6 +13,7 @@ nullabilityAnnotations = "16.0.2"
 macOSFramework = "latest.release"
 javaNativeFoundation = "1.1.1"
 errorprone = "2.8.1"
+errorproneCompiler = "9+181-r4173-1"
 guava = "1.0"
 javaxAnnotations = "1.3.2"
 
@@ -48,6 +49,7 @@ test-jna = { module = "net.java.dev.jna:jna", version.ref = "jna" }
 tools-errorprone-core = { module = "com.google.errorprone:error_prone_core", version.ref = "errorprone" }
 tools-errorprone-annotations = { module = "com.google.errorprone:error_prone_annotations", version.ref = "errorprone" }
 tools-errorprone-guava = { module = "com.google.guava:guava-beta-checker", version.ref = "guava" }
+tools-errorprone-javac = { module = "com.google.errorprone:javac", version.ref = "errorproneCompiler" }
 
 [bundles]
 test-miglayout = ["test-miglayout-core", "test-miglayout-swing"]