Add missing Javadoc.

src/main/java/org/apache/commons/lang3/concurrent/AbstractCircuitBreaker.java

@@ -27,6 +27,7 @@ import java.util.concurrent.atomic.AtomicReference;
  * @since 3.5
  */
 public abstract class AbstractCircuitBreaker<T> implements CircuitBreaker<T> {
+
     /**
      * The name of the <em>open</em> property as it is passed to registered
      * change listeners.
@@ -139,6 +140,8 @@ public abstract class AbstractCircuitBreaker<T> implements CircuitBreaker<T> {
      * {@code CircuitBreaker}.
      */
     protected enum State {
+        
+        /** The closed state. */
         CLOSED {
             /**
              * {@inheritDoc}
@@ -149,6 +152,7 @@ public abstract class AbstractCircuitBreaker<T> implements CircuitBreaker<T> {
             }
         },
 
+        /** The open state. */
         OPEN {
             /**
              * {@inheritDoc}

src/main/java/org/apache/commons/lang3/stream/Streams.java

@@ -66,10 +66,20 @@ import org.apache.commons.lang3.function.FailablePredicate;
  */
 public class Streams {
 
+    /**
+     * A Collector type for arrays.
+     *
+     * @param <O> The array type.
+     */
     public static class ArrayCollector<O> implements Collector<O, List<O>, O[]> {
         private static final Set<Characteristics> characteristics = Collections.emptySet();
         private final Class<O> elementType;
 
+        /**
+         * Constructs a new instance for the given element type.
+         *
+         * @param elementType The element type.
+         */
         public ArrayCollector(final Class<O> elementType) {
             this.elementType = elementType;
         }

src/main/java/org/apache/commons/lang3/text/translate/NumericEntityUnescaper.java

@@ -36,8 +36,23 @@ import java.util.EnumSet;
 @Deprecated
 public class NumericEntityUnescaper extends CharSequenceTranslator {
 
+    /** Enumerates NumericEntityUnescaper options for unescaping. */
     public enum OPTION {
-        semiColonRequired, semiColonOptional, errorIfNoSemiColon
+
+        /**
+         * Require a semicolon.
+         */
+        semiColonRequired,
+
+        /**
+         * Do not require a semicolon.
+         */
+        semiColonOptional,
+
+        /**
+         * Throw an exception if a semi-colon is missing.
+         */
+        errorIfNoSemiColon
     }
 
     // TODO?: Create an OptionsSet class to hide some of the conditional logic below