XJC ConstField generates empty javadoc comment blocks

[patrodyne]

As of v4.0.4, the ConstField class generates empty Javadoc comment blocks when no <javadoc>text</javadoc> is explicitly provided in the XML schema.

Example: Empty Javadoc for a Constant Field

    /**
     * 
     * 
     */
    @XmlAttribute(name = "fa_long")
    public static final boolean FA_LONG = 7L;

A fix is to conditionally append the prop.javadoc only when it has content:

--- a/jaxb-ri/xjc/src/main/java/com/sun/tools/xjc/generator/bean/field/ConstField.java
+++ b/jaxb-ri/xjc/src/main/java/com/sun/tools/xjc/generator/bean/field/ConstField.java
@@ -54,8 +54,11 @@ final class ConstField extends AbstractField {
 
         $ref = outline.ref.field(JMod.PUBLIC|JMod.STATIC|JMod.FINAL,
             ptype!=null?ptype:implType, prop.getName(true), defaultValue );
-        $ref.javadoc().append(prop.javadoc);
         
+        // Do not append empty javadoc.
+        if ( (prop.javadoc != null) && (prop.javadoc.length() > 0) )
+            $ref.javadoc().append(prop.javadoc);
+
         annotate($ref);
     }

Rationale

Currently, when $ref.javadoc() is invoked by ConstField, the jdoc field of JFieldVar is initialized to a non-null value. Later, the declare method is invoked and the JFormatter.g(jdoc) method is triggered whenever jdoc is not null. This leads to a call to JDocComment.generate(JFormatter) which includes blank lines when @param, @return, @throws, etc. are not applicable.

The proposed fix is to prevent an unnecessary initialization of the jdoc field of JFieldVar; thus, avoiding a call to JDocComment.generate(JFormatter). I will submit a pull request with the fix and a unit test.

ConstField: Call Sequence

com.sun.codemodel.JFieldVar.javadoc()
	...
    public JDocComment javadoc()
	{
        if( jdoc == null ) 
            jdoc = new JDocComment(owner.owner());
        return jdoc;
    }
	...
com.sun.codemodel.JDefinedClass.declareBody(JFormatter)
com.sun.codemodel.JFormatter.d(JDeclaration)
com.sun.codemodel.JFieldVar.declare(JFormatter)
	...
    public void declare(JFormatter f)
	{
        if( jdoc != null )
            f.g( jdoc );
        super.declare( f );
    }
	...
com.sun.codemodel.JFormatter.g(JGenerable)
com.sun.codemodel.JDocComment.generate(JFormatter)