code changes to remove bad file extension check

src/main/java/gov/nasa/pds/tools/validate/InMemoryRegistrar.java

@@ -216,11 +216,6 @@ public synchronized Collection<String> getUnreferencedTargets() {
     return unreferencedTargets;
   }
 
-  @Override
-  public synchronized Collection<Identifier> getReferencedIdentifiers() {
-    return referencedIdentifiers;
-  }
-
   @Override
   public synchronized Collection<Identifier> getUnreferencedIdentifiers() {
     List<Identifier> unreferencedIdentifiers = new ArrayList<>();

src/main/java/gov/nasa/pds/tools/validate/TargetRegistrar.java

@@ -166,7 +166,6 @@ public interface TargetRegistrar {
    *
    * @return a collection of referenced identifiers.
    */
-  Collection<Identifier> getReferencedIdentifiers();
 
   /**
    * Gets the location of where the given identifier is referenced.

src/main/java/gov/nasa/pds/tools/validate/rule/pds4/CollectionReferentialIntegrityRule.java

@@ -75,12 +75,7 @@ public void collectionReferentialIntegrityRule() {
       LOG.debug("collectionReferentialIntegrityRule:getTarget() {}, num collections {}",
           getTarget(), collections.keySet().size());
 
-      // Check for collection(_.*)?\.(xml or lblx) file.
       for (Map.Entry<String, ValidationTarget> collection : collections.entrySet()) {
-        if (!collection.getValue().getLocation().endsWith(getContext().getLabelExtension())) {
-          continue;
-        }
-
         Target collectionTarget = new Target(collection.getValue().getUrl(), false);
         try {
           XMLExtractor extractor = new XMLExtractor(collectionTarget.getUrl());