This proposal is an update to 4421066. It modifies an interface
 change that has not yet been publically released.


 Background

 The javadoc tool maintains backward compatibility for "legacy" doclets --
 those not aware of the Tiger language features. It modifies the
 results of a number of methods to match as closely as possible the
 pre-Tiger results. For example, type parameters are elided.

 The javadoc tool must be able to determine if a doclet supports the
 1.5 language features. It currently relies on a marker interface
 Doclet15 for new doclets to implement. The name Doclet15, and
 its use as a marker interface, are ugly and nonintuitive. It would be
 ideal if we could have a Doclet interface for doclets to implement.
 Unfortunately the class name Doclet is already taken by a so-called
 "example" doclet, and the entry point methods of a doclet are all (for
 no good reason) static.


 Proposal

 Drop Doclet15. Instead, a doclet should indicate its language version
 by supplying a languageVersion method. This has the side benefit of
 being extensible for possible language changes in, say, Mustang. The
 "example" Doclet class has the following addition:

     /**
      * Return the version of the Java Programming Language supported
      * by this doclet.
      * <p>
      * This method is required by any doclet supporting a language version
      * other than 1.1.
      *
      * @return the language version supported by this doclet;
      * default is 1.1
      * @since 1.5
      */
     public static LanguageVersion languageVersion() {
return LanguageVersion.JDK1_1;
     }

 LanguageVersion is defined as:

     /**
      * Java Programming Language version. The constants of this enum
      * identify the JDK and J2SE releases containing language changes
      * relevant to doclets.
      * <p>
      * All doclets support at least the 1.1 language version.
      * The first release subsequent to this with language changes
      * affecting doclets is 1.5.
      *
      * @since 1.5
      */
     public enum LanguageVersion {

/** JDK 1.1: added nested classes and interfaces. */
JDK1_1,

/** J2SE 1.5: added generic types, enums, varargs, and annotations. */
J2SE1_5
     }