fix(multirelease): Correct handling of exclusions when checking module exports

Author: zml2008

indra-common/src/main/java/net/kyori/indra/task/CheckModuleExports.java

@@ -130,7 +130,7 @@ public void validateModule() throws IOException {
   private Set<String> checkExports(final Set<String> exported, final Set<String> known, final Set<String> excludedPrefixes) {
     final Set<String> problems = new HashSet<>(known);
     problems.removeAll(exported);
-    for (final Iterator<String> it = known.iterator(); it.hasNext();) {
+    for (final Iterator<String> it = problems.iterator(); it.hasNext();) {
       final String check = it.next();
       for (final String prefix : excludedPrefixes) {
         if (check.startsWith(prefix)) {