diff --git a/src/main/java/org/apache/commons/collections4/CollectionUtils.java b/src/main/java/org/apache/commons/collections4/CollectionUtils.java
index 1990c3798d..393f1ee88a 100644
--- a/src/main/java/org/apache/commons/collections4/CollectionUtils.java
+++ b/src/main/java/org/apache/commons/collections4/CollectionUtils.java
@@ -560,7 +560,7 @@ public static <I, O, R extends Collection<? super O>> R collect(final Iterator<?
         if (inputIterator != null && transformer != null) {
             while (inputIterator.hasNext()) {
                 final I item = inputIterator.next();
-                final O value = transformer.transform(item);
+                final O value = transformer.apply(item);
                 outputCollection.add(value);
             }
         }
@@ -2068,7 +2068,7 @@ public static <C> void transform(final Collection<C> collection,
             if (collection instanceof List<?>) {
                 final List<C> list = (List<C>) collection;
                 for (final ListIterator<C> it = list.listIterator(); it.hasNext();) {
-                    it.set(transformer.transform(it.next()));
+                    it.set(transformer.apply(it.next()));
                 }
             } else {
                 final Collection<C> resultCollection = collect(collection, transformer);
diff --git a/src/main/java/org/apache/commons/collections4/IteratorUtils.java b/src/main/java/org/apache/commons/collections4/IteratorUtils.java
index 856c4b8572..10e244544d 100644
--- a/src/main/java/org/apache/commons/collections4/IteratorUtils.java
+++ b/src/main/java/org/apache/commons/collections4/IteratorUtils.java
@@ -1312,7 +1312,7 @@ public static <E> String toString(final Iterator<E> iterator,
         if (iterator != null) {
             while (iterator.hasNext()) {
                 final E element = iterator.next();
-                stringBuilder.append(transformer.transform(element));
+                stringBuilder.append(transformer.apply(element));
                 stringBuilder.append(delimiter);
             }
             if (stringBuilder.length() > prefix.length()) {
diff --git a/src/main/java/org/apache/commons/collections4/MapUtils.java b/src/main/java/org/apache/commons/collections4/MapUtils.java
index 9fa8a7a52f..ccd4102cad 100644
--- a/src/main/java/org/apache/commons/collections4/MapUtils.java
+++ b/src/main/java/org/apache/commons/collections4/MapUtils.java
@@ -1497,7 +1497,7 @@ public static <K, V> OrderedMap<K, V> orderedMap(final Map<K, V> map) {
     public static <K, V, E> void populateMap(final Map<K, V> map, final Iterable<? extends E> elements,
             final Transformer<E, K> keyTransformer, final Transformer<E, V> valueTransformer) {
         for (final E temp : elements) {
-            map.put(keyTransformer.transform(temp), valueTransformer.transform(temp));
+            map.put(keyTransformer.apply(temp), valueTransformer.apply(temp));
         }
     }
 
@@ -1532,7 +1532,7 @@ public static <K, V> void populateMap(final Map<K, V> map, final Iterable<? exte
     public static <K, V, E> void populateMap(final MultiMap<K, V> map, final Iterable<? extends E> elements,
             final Transformer<E, K> keyTransformer, final Transformer<E, V> valueTransformer) {
         for (final E temp : elements) {
-            map.put(keyTransformer.transform(temp), valueTransformer.transform(temp));
+            map.put(keyTransformer.apply(temp), valueTransformer.apply(temp));
         }
     }
 
diff --git a/src/main/java/org/apache/commons/collections4/bag/TransformedBag.java b/src/main/java/org/apache/commons/collections4/bag/TransformedBag.java
index 883070e8c8..ada438425c 100644
--- a/src/main/java/org/apache/commons/collections4/bag/TransformedBag.java
+++ b/src/main/java/org/apache/commons/collections4/bag/TransformedBag.java
@@ -65,7 +65,7 @@ public static <E> Bag<E> transformedBag(final Bag<E> bag, final Transformer<? su
             final E[] values = (E[]) bag.toArray(); // NOPMD - false positive for generics
             bag.clear();
             for (final E value : values) {
-                decorated.decorated().add(transformer.transform(value));
+                decorated.decorated().add(transformer.apply(value));
             }
         }
         return decorated;
diff --git a/src/main/java/org/apache/commons/collections4/bag/TransformedSortedBag.java b/src/main/java/org/apache/commons/collections4/bag/TransformedSortedBag.java
index 10ec158cb3..6da66ecfaf 100644
--- a/src/main/java/org/apache/commons/collections4/bag/TransformedSortedBag.java
+++ b/src/main/java/org/apache/commons/collections4/bag/TransformedSortedBag.java
@@ -65,7 +65,7 @@ public static <E> TransformedSortedBag<E> transformedSortedBag(final SortedBag<E
             final E[] values = (E[]) bag.toArray(); // NOPMD - false positive for generics
             bag.clear();
             for (final E value : values) {
-                decorated.decorated().add(transformer.transform(value));
+                decorated.decorated().add(transformer.apply(value));
             }
         }
         return decorated;
diff --git a/src/main/java/org/apache/commons/collections4/collection/IndexedCollection.java b/src/main/java/org/apache/commons/collections4/collection/IndexedCollection.java
index 1cab5556c9..dec686f5fb 100644
--- a/src/main/java/org/apache/commons/collections4/collection/IndexedCollection.java
+++ b/src/main/java/org/apache/commons/collections4/collection/IndexedCollection.java
@@ -145,7 +145,7 @@ public boolean addAll(final Collection<? extends C> coll) {
      *   enforces a uniqueness constraint
      */
     private void addToIndex(final C object) {
-        final K key = keyTransformer.transform(object);
+        final K key = keyTransformer.apply(object);
         if (uniqueIndex && index.containsKey(key)) {
             throw new IllegalArgumentException("Duplicate key in uniquely indexed collection.");
         }
@@ -166,7 +166,7 @@ public void clear() {
     @SuppressWarnings("unchecked")
     @Override
     public boolean contains(final Object object) {
-        return index.containsKey(keyTransformer.transform((C) object));
+        return index.containsKey(keyTransformer.apply((C) object));
     }
 
     /**
@@ -236,7 +236,7 @@ public boolean removeAll(final Collection<?> coll) {
      * @param object the object to remove
      */
     private void removeFromIndex(final C object) {
-        index.remove(keyTransformer.transform(object));
+        index.remove(keyTransformer.apply(object));
     }
 
     /**
diff --git a/src/main/java/org/apache/commons/collections4/collection/TransformedCollection.java b/src/main/java/org/apache/commons/collections4/collection/TransformedCollection.java
index c30c591cdc..456b33a53e 100644
--- a/src/main/java/org/apache/commons/collections4/collection/TransformedCollection.java
+++ b/src/main/java/org/apache/commons/collections4/collection/TransformedCollection.java
@@ -68,7 +68,7 @@ public static <E> TransformedCollection<E> transformedCollection(final Collectio
             final E[] values = (E[]) collection.toArray(); // NOPMD - false positive for generics
             collection.clear();
             for (final E value : values) {
-                decorated.decorated().add(transformer.transform(value));
+                decorated.decorated().add(transformer.apply(value));
             }
         }
         return decorated;
@@ -146,7 +146,7 @@ protected Collection<E> transform(final Collection<? extends E> coll) {
      * @return a transformed object
      */
     protected E transform(final E object) {
-        return transformer.transform(object);
+        return transformer.apply(object);
     }
 
 }
diff --git a/src/main/java/org/apache/commons/collections4/comparators/TransformingComparator.java b/src/main/java/org/apache/commons/collections4/comparators/TransformingComparator.java
index fa873bb94d..74adfdb7e9 100644
--- a/src/main/java/org/apache/commons/collections4/comparators/TransformingComparator.java
+++ b/src/main/java/org/apache/commons/collections4/comparators/TransformingComparator.java
@@ -81,8 +81,8 @@ public TransformingComparator(final Transformer<? super I, ? extends O> transfor
      */
     @Override
     public int compare(final I obj1, final I obj2) {
-        final O value1 = this.transformer.transform(obj1);
-        final O value2 = this.transformer.transform(obj2);
+        final O value1 = this.transformer.apply(obj1);
+        final O value2 = this.transformer.apply(obj2);
         return this.decorated.compare(value1, value2);
     }
 
diff --git a/src/main/java/org/apache/commons/collections4/functors/ChainedTransformer.java b/src/main/java/org/apache/commons/collections4/functors/ChainedTransformer.java
index d2e21147c0..444f5bf919 100644
--- a/src/main/java/org/apache/commons/collections4/functors/ChainedTransformer.java
+++ b/src/main/java/org/apache/commons/collections4/functors/ChainedTransformer.java
@@ -120,7 +120,7 @@ public ChainedTransformer(final Transformer<? super T, ? extends T>... transform
     @Override
     public T transform(T object) {
         for (final Transformer<? super T, ? extends T> iTransformer : iTransformers) {
-            object = iTransformer.transform(object);
+            object = iTransformer.apply(object);
         }
         return object;
     }
diff --git a/src/main/java/org/apache/commons/collections4/functors/IfTransformer.java b/src/main/java/org/apache/commons/collections4/functors/IfTransformer.java
index ddf4a532a2..787c43ae46 100644
--- a/src/main/java/org/apache/commons/collections4/functors/IfTransformer.java
+++ b/src/main/java/org/apache/commons/collections4/functors/IfTransformer.java
@@ -134,8 +134,8 @@ public Predicate<? super I> getPredicate() {
     @Override
     public O transform(final I input) {
         if (iPredicate.test(input)) {
-            return iTrueTransformer.transform(input);
+            return iTrueTransformer.apply(input);
         }
-        return iFalseTransformer.transform(input);
+        return iFalseTransformer.apply(input);
     }
 }
diff --git a/src/main/java/org/apache/commons/collections4/functors/SwitchTransformer.java b/src/main/java/org/apache/commons/collections4/functors/SwitchTransformer.java
index 3954439525..eb3dbfa959 100644
--- a/src/main/java/org/apache/commons/collections4/functors/SwitchTransformer.java
+++ b/src/main/java/org/apache/commons/collections4/functors/SwitchTransformer.java
@@ -188,10 +188,10 @@ public Predicate<? super I>[] getPredicates() {
     public O transform(final I input) {
         for (int i = 0; i < iPredicates.length; i++) {
             if (iPredicates[i].test(input)) {
-                return iTransformers[i].transform(input);
+                return iTransformers[i].apply(input);
             }
         }
-        return iDefault.transform(input);
+        return iDefault.apply(input);
     }
 
 }
diff --git a/src/main/java/org/apache/commons/collections4/functors/TransformedPredicate.java b/src/main/java/org/apache/commons/collections4/functors/TransformedPredicate.java
index 8fe496e127..7b19ce342e 100644
--- a/src/main/java/org/apache/commons/collections4/functors/TransformedPredicate.java
+++ b/src/main/java/org/apache/commons/collections4/functors/TransformedPredicate.java
@@ -77,7 +77,7 @@ public TransformedPredicate(final Transformer<? super T, ? extends T> transforme
      */
     @Override
     public boolean test(final T object) {
-        final T result = iTransformer.transform(object);
+        final T result = iTransformer.apply(object);
         return iPredicate.test(result);
     }
 
diff --git a/src/main/java/org/apache/commons/collections4/functors/TransformerClosure.java b/src/main/java/org/apache/commons/collections4/functors/TransformerClosure.java
index 8a528030ff..6d47fde5a5 100644
--- a/src/main/java/org/apache/commons/collections4/functors/TransformerClosure.java
+++ b/src/main/java/org/apache/commons/collections4/functors/TransformerClosure.java
@@ -69,7 +69,7 @@ public TransformerClosure(final Transformer<? super T, ?> transformer) {
      */
     @Override
     public void execute(final T input) {
-        iTransformer.transform(input);
+        iTransformer.apply(input);
     }
 
     /**
diff --git a/src/main/java/org/apache/commons/collections4/functors/TransformerPredicate.java b/src/main/java/org/apache/commons/collections4/functors/TransformerPredicate.java
index ff5c796d97..e40b014d77 100644
--- a/src/main/java/org/apache/commons/collections4/functors/TransformerPredicate.java
+++ b/src/main/java/org/apache/commons/collections4/functors/TransformerPredicate.java
@@ -68,7 +68,7 @@ public TransformerPredicate(final Transformer<? super T, Boolean> transformer) {
      */
     @Override
     public boolean test(final T object) {
-        final Boolean result = iTransformer.transform(object);
+        final Boolean result = iTransformer.apply(object);
         if (result == null) {
             throw new FunctorException(
                     "Transformer must return an instanceof Boolean, it was a null object");
diff --git a/src/main/java/org/apache/commons/collections4/iterators/ObjectGraphIterator.java b/src/main/java/org/apache/commons/collections4/iterators/ObjectGraphIterator.java
index 0ec9a7c276..b094b4b477 100644
--- a/src/main/java/org/apache/commons/collections4/iterators/ObjectGraphIterator.java
+++ b/src/main/java/org/apache/commons/collections4/iterators/ObjectGraphIterator.java
@@ -160,7 +160,7 @@ protected void findNextByIterator(final Iterator<? extends E> iterator) {
         while (currentIterator.hasNext() && !hasNext) {
             E next = currentIterator.next();
             if (transformer != null) {
-                next = transformer.transform(next);
+                next = transformer.apply(next);
             }
             findNext(next);
         }
@@ -238,7 +238,7 @@ protected void updateCurrentIterator() {
                 if (transformer == null) {
                     findNext(root);
                 } else {
-                    findNext(transformer.transform(root));
+                    findNext(transformer.apply(root));
                 }
                 root = null;
             }
diff --git a/src/main/java/org/apache/commons/collections4/iterators/TransformIterator.java b/src/main/java/org/apache/commons/collections4/iterators/TransformIterator.java
index 668afc2f19..03f1a02099 100644
--- a/src/main/java/org/apache/commons/collections4/iterators/TransformIterator.java
+++ b/src/main/java/org/apache/commons/collections4/iterators/TransformIterator.java
@@ -133,6 +133,6 @@ public void setTransformer(final Transformer<? super I, ? extends O> transformer
      * @return the transformed object
      */
     protected O transform(final I source) {
-        return transformer.transform(source);
+        return transformer.apply(source);
     }
 }
diff --git a/src/main/java/org/apache/commons/collections4/list/LazyList.java b/src/main/java/org/apache/commons/collections4/list/LazyList.java
index 3add8c96f3..70ccd78d9d 100644
--- a/src/main/java/org/apache/commons/collections4/list/LazyList.java
+++ b/src/main/java/org/apache/commons/collections4/list/LazyList.java
@@ -134,7 +134,7 @@ private E element(final int index) {
             return factory.get();
         }
         if (transformer != null) {
-            return transformer.transform(index);
+            return transformer.apply(index);
         }
         throw new IllegalStateException("Factory and Transformer are both null!");
     }
diff --git a/src/main/java/org/apache/commons/collections4/list/TransformedList.java b/src/main/java/org/apache/commons/collections4/list/TransformedList.java
index b90505ad1f..e1860fb3a4 100644
--- a/src/main/java/org/apache/commons/collections4/list/TransformedList.java
+++ b/src/main/java/org/apache/commons/collections4/list/TransformedList.java
@@ -93,7 +93,7 @@ public static <E> TransformedList<E> transformedList(final List<E> list,
             final E[] values = (E[]) list.toArray(); // NOPMD - false positive for generics
             list.clear();
             for (final E value : values) {
-                decorated.decorated().add(transformer.transform(value));
+                decorated.decorated().add(transformer.apply(value));
             }
         }
         return decorated;
diff --git a/src/main/java/org/apache/commons/collections4/map/DefaultedMap.java b/src/main/java/org/apache/commons/collections4/map/DefaultedMap.java
index a46d3c829c..86fe2fa9ce 100644
--- a/src/main/java/org/apache/commons/collections4/map/DefaultedMap.java
+++ b/src/main/java/org/apache/commons/collections4/map/DefaultedMap.java
@@ -173,7 +173,7 @@ public V get(final Object key) {
         final V v;
         return (v = map.get(key)) != null || map.containsKey(key)
             ? v
-            : value.transform((K) key);
+            : value.apply((K) key);
     }
 
     /**
diff --git a/src/main/java/org/apache/commons/collections4/map/LazyMap.java b/src/main/java/org/apache/commons/collections4/map/LazyMap.java
index 1577eb35b2..24ad6432c5 100644
--- a/src/main/java/org/apache/commons/collections4/map/LazyMap.java
+++ b/src/main/java/org/apache/commons/collections4/map/LazyMap.java
@@ -135,7 +135,7 @@ public V get(final Object key) {
         if (!map.containsKey(key)) {
             @SuppressWarnings("unchecked")
             final K castKey = (K) key;
-            final V value = factory.transform(castKey);
+            final V value = factory.apply(castKey);
             map.put(castKey, value);
             return value;
         }
diff --git a/src/main/java/org/apache/commons/collections4/map/MultiValueMap.java b/src/main/java/org/apache/commons/collections4/map/MultiValueMap.java
index 607acd5e76..b80ce92f32 100644
--- a/src/main/java/org/apache/commons/collections4/map/MultiValueMap.java
+++ b/src/main/java/org/apache/commons/collections4/map/MultiValueMap.java
@@ -315,7 +315,7 @@ public boolean containsValue(final Object key, final Object value) {
      * @return the new collection
      */
     protected Collection<V> createCollection(final int size) {
-        return collectionFactory.create();
+        return collectionFactory.get();
     }
 
     /**
diff --git a/src/main/java/org/apache/commons/collections4/map/TransformedMap.java b/src/main/java/org/apache/commons/collections4/map/TransformedMap.java
index 80f165f7b7..f7e1768f2d 100644
--- a/src/main/java/org/apache/commons/collections4/map/TransformedMap.java
+++ b/src/main/java/org/apache/commons/collections4/map/TransformedMap.java
@@ -139,7 +139,7 @@ protected TransformedMap(final Map<K, V> map, final Transformer<? super K, ? ext
      */
     @Override
     protected V checkSetValue(final V value) {
-        return valueTransformer.transform(value);
+        return valueTransformer.apply(value);
     }
 
     /**
@@ -192,7 +192,7 @@ protected K transformKey(final K object) {
         if (keyTransformer == null) {
             return object;
         }
-        return keyTransformer.transform(object);
+        return keyTransformer.apply(object);
     }
 
     /**
@@ -228,7 +228,7 @@ protected V transformValue(final V object) {
         if (valueTransformer == null) {
             return object;
         }
-        return valueTransformer.transform(object);
+        return valueTransformer.apply(object);
     }
 
     /**
diff --git a/src/main/java/org/apache/commons/collections4/multimap/TransformedMultiValuedMap.java b/src/main/java/org/apache/commons/collections4/multimap/TransformedMultiValuedMap.java
index e0270c1522..03174edaeb 100644
--- a/src/main/java/org/apache/commons/collections4/multimap/TransformedMultiValuedMap.java
+++ b/src/main/java/org/apache/commons/collections4/multimap/TransformedMultiValuedMap.java
@@ -167,7 +167,7 @@ protected K transformKey(final K object) {
         if (keyTransformer == null) {
             return object;
         }
-        return keyTransformer.transform(object);
+        return keyTransformer.apply(object);
     }
 
     /**
@@ -182,7 +182,7 @@ protected V transformValue(final V object) {
         if (valueTransformer == null) {
             return object;
         }
-        return valueTransformer.transform(object);
+        return valueTransformer.apply(object);
     }
 
 }
diff --git a/src/main/java/org/apache/commons/collections4/queue/TransformedQueue.java b/src/main/java/org/apache/commons/collections4/queue/TransformedQueue.java
index 802ef3d177..f9583e0e3c 100644
--- a/src/main/java/org/apache/commons/collections4/queue/TransformedQueue.java
+++ b/src/main/java/org/apache/commons/collections4/queue/TransformedQueue.java
@@ -62,7 +62,7 @@ public static <E> TransformedQueue<E> transformedQueue(final Queue<E> queue,
             final E[] values = (E[]) queue.toArray(); // NOPMD - false positive for generics
             queue.clear();
             for (final E value : values) {
-                decorated.decorated().add(transformer.transform(value));
+                decorated.decorated().add(transformer.apply(value));
             }
         }
         return decorated;
diff --git a/src/main/java/org/apache/commons/collections4/set/TransformedNavigableSet.java b/src/main/java/org/apache/commons/collections4/set/TransformedNavigableSet.java
index df4c28fb49..02a05ba22a 100644
--- a/src/main/java/org/apache/commons/collections4/set/TransformedNavigableSet.java
+++ b/src/main/java/org/apache/commons/collections4/set/TransformedNavigableSet.java
@@ -61,7 +61,7 @@ public static <E> TransformedNavigableSet<E> transformedNavigableSet(final Navig
             final E[] values = (E[]) set.toArray(); // NOPMD - false positive for generics
             set.clear();
             for (final E value : values) {
-                decorated.decorated().add(transformer.transform(value));
+                decorated.decorated().add(transformer.apply(value));
             }
         }
         return decorated;
diff --git a/src/main/java/org/apache/commons/collections4/set/TransformedSet.java b/src/main/java/org/apache/commons/collections4/set/TransformedSet.java
index f217dfbd13..ed38468998 100644
--- a/src/main/java/org/apache/commons/collections4/set/TransformedSet.java
+++ b/src/main/java/org/apache/commons/collections4/set/TransformedSet.java
@@ -63,7 +63,7 @@ public static <E> Set<E> transformedSet(final Set<E> set, final Transformer<? su
             final E[] values = (E[]) set.toArray(); // NOPMD - false positive for generics
             set.clear();
             for (final E value : values) {
-                decorated.decorated().add(transformer.transform(value));
+                decorated.decorated().add(transformer.apply(value));
             }
         }
         return decorated;
diff --git a/src/main/java/org/apache/commons/collections4/set/TransformedSortedSet.java b/src/main/java/org/apache/commons/collections4/set/TransformedSortedSet.java
index 19067f2e06..c2e8acdbfe 100644
--- a/src/main/java/org/apache/commons/collections4/set/TransformedSortedSet.java
+++ b/src/main/java/org/apache/commons/collections4/set/TransformedSortedSet.java
@@ -65,7 +65,7 @@ public static <E> TransformedSortedSet<E> transformedSortedSet(final SortedSet<E
             final E[] values = (E[]) set.toArray(); // NOPMD - false positive for generics
             set.clear();
             for (final E value : values) {
-                decorated.decorated().add(transformer.transform(value));
+                decorated.decorated().add(transformer.apply(value));
             }
         }
         return decorated;
diff --git a/src/main/java/org/apache/commons/collections4/splitmap/TransformedSplitMap.java b/src/main/java/org/apache/commons/collections4/splitmap/TransformedSplitMap.java
index cc7f07dee9..ea923178e4 100644
--- a/src/main/java/org/apache/commons/collections4/splitmap/TransformedSplitMap.java
+++ b/src/main/java/org/apache/commons/collections4/splitmap/TransformedSplitMap.java
@@ -124,7 +124,7 @@ protected TransformedSplitMap(final Map<K, V> map, final Transformer<? super J,
      * @return the transformed value
      */
     protected V checkSetValue(final U value) {
-        return valueTransformer.transform(value);
+        return valueTransformer.apply(value);
     }
 
     @Override
@@ -165,7 +165,7 @@ private void readObject(final ObjectInputStream in) throws IOException, ClassNot
      * @return the transformed object
      */
     protected K transformKey(final J object) {
-        return keyTransformer.transform(object);
+        return keyTransformer.apply(object);
     }
 
     /**
@@ -198,7 +198,7 @@ protected Map<K, V> transformMap(final Map<? extends J, ? extends U> map) {
      * @return the transformed object
      */
     protected V transformValue(final U object) {
-        return valueTransformer.transform(object);
+        return valueTransformer.apply(object);
     }
 
     /**