Use root project layout for retrieving editorconfig

Author: inorichi

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/BaseKotlinExtension.java

@@ -162,9 +162,7 @@ private KtlintConfig(
 				Map<String, Object> editorConfigOverride,
 				List<String> customRuleSets) throws IOException {
 			Objects.requireNonNull(version);
-			@SuppressWarnings("UnstableApiUsage")
-			Directory rootProjectDir = getProject().getIsolated().getRootProject().getProjectDirectory();
-			File defaultEditorConfig = rootProjectDir.file(".editorconfig").getAsFile();
+			File defaultEditorConfig = getProject().getRootProject().getLayout().getProjectDirectory().file(".editorconfig").getAsFile();
 			FileSignature editorConfigPath = defaultEditorConfig.exists() ? FileSignature.signAsList(defaultEditorConfig) : null;
 			this.version = version;
 			this.editorConfigPath = editorConfigPath;