javadoc clarification wrt [JACKSON-920]

src/main/java/com/fasterxml/jackson/annotation/JsonCreator.java

@@ -26,6 +26,10 @@
  * Also note that all {@link JsonProperty} annotations MUST use actual name
  * (NOT empty String for "default"): this because Java bytecode does not
  * retain names of method or constructor arguments.
+ *<br />
+ * NOTE: as of JDK 8, some of above changes, with introduction of names for
+ * constructor and method parameters.
+ *
  */
 @Target({ElementType.ANNOTATION_TYPE, ElementType.METHOD, ElementType.CONSTRUCTOR})
 @Retention(RetentionPolicy.RUNTIME)

src/main/java/com/fasterxml/jackson/annotation/JsonInclude.java

@@ -78,6 +78,8 @@ public enum Include
          * Value that indicates that only properties that have values
          * that values that are null or what is considered empty are
          * not to be included.
+         * Definition of emptiness is data type specific; see below
+         * for details on actual handling.
          *<p>
          * Default emptiness is defined for following type:
          *<ul>
@@ -90,8 +92,11 @@ public enum Include
          *   and return value of 0 indicates empty String (note that <code>String.isEmpty()</code>
          *   was added in Java 1.6 and as such can not be used by Jackson
          *   </li>
+         * <li>For date/time types, if timestamp from Epoch is zero (January 1st, 1970, UTC),
+         *    value is considered empty.
+         *   </li>
          * <ul>
-         *  and for other types, non-null values are to be included.
+         *  and for other types, null values are excluded but other exclusions (if any).
          *<p>
          * Note that this default handling can be overridden by custom
          * <code>JsonSerializer</code> implementation: if method <code>isEmpty()</code>