Remove redundant 'static' modifiers

enums, interfaces, and field members in interfaces are by default
static, so don't need to be explicitly declared so.

Change-Id: I29270c28be30965767519ad0105a7d93a24e0ab4

gerrit-server/src/main/java/com/google/gerrit/rules/PrologEnvironment.java

@@ -54,7 +54,7 @@ public class PrologEnvironment extends BufferingPrologControl {
   private static final Logger log =
       LoggerFactory.getLogger(PrologEnvironment.class);
 
-  public static interface Factory {
+  public interface Factory {
     /**
      * Construct a new Prolog interpreter.
      *