Reduce visibility

Co-authored-by: Zongle Wang <[email protected]>

Author: mches

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

@@ -51,7 +51,7 @@ public SortPomGradleConfig sortPom(String version) {
 	}
 
 	public class SortPomGradleConfig {
-		final SortPomCfg cfg = new SortPomCfg();
+		private final SortPomCfg cfg = new SortPomCfg();
 
 		SortPomGradleConfig() {
 			addStep(createStep());