Javadoc: Add missing generic types

src/main/java/org/apache/commons/collections4/map/ConcurrentReferenceHashMap.java

@@ -668,6 +668,9 @@ public enum ReferenceType {
      * <p>
      * As a guide, all critical volatile reads and writes to the count field are marked in code comments.
      * </p>
+     *
+     * @param <K> the type of keys maintained by this Segment.
+     * @param <V> the type of mapped values.
      */
     private static final class Segment<K, V> extends ReentrantLock {
 

src/main/java/org/apache/commons/collections4/map/SingletonMap.java

@@ -150,6 +150,8 @@ public String toString() {
     /**
      * Values implementation for the SingletonMap.
      * This class is needed as values is a view that must update as the map updates.
+     *
+     * @param <V> the type of the values in this set.
      */
     static class SingletonValues<V> extends AbstractSet<V> implements Serializable {
         private static final long serialVersionUID = -3689524741863047872L;

src/main/java/org/apache/commons/collections4/multiset/SynchronizedMultiSet.java

@@ -29,13 +29,15 @@
  * Iterators must be separately synchronized around the loop.
  * </p>
  *
- * @param <E> the type held in the multiset
+ * @param <E> the type held in the multiset.
  * @since 4.1
  */
 public class SynchronizedMultiSet<E> extends SynchronizedCollection<E> implements MultiSet<E> {
 
     /**
      * Synchronized Set for the MultiSet class.
+     *
+     * @param <T> the type held in this Set.
      */
     static class SynchronizedSet<T> extends SynchronizedCollection<T> implements Set<T> {
         /** Serialization version */

src/main/java/org/apache/commons/collections4/trie/AbstractBitwiseTrie.java

@@ -36,6 +36,9 @@ public abstract class AbstractBitwiseTrie<K, V> extends AbstractMap<K, V>
 
     /**
      * A basic implementation of {@link Entry}.
+     *
+     * @param <K> the type of the keys in this entry.
+     * @param <V> the type of the values in this entry.
      */
     abstract static class BasicEntry<K, V> implements Map.Entry<K, V>, Serializable {