code: private FieldDoc getFieldDoc(Configuration config, Tag tag, String name) {
          if (name == null || name.length() == 0) {
              //Base case: no label.
              if (tag.holder() instanceof FieldDoc) {
                  return (FieldDoc) tag.holder();
              } else {
                  // If the value tag does not specify a parameter which is a valid field and
                  // it is not used within the comments of a valid field, return null.
                   return null;
              }
          }
          StringTokenizer st = new StringTokenizer(name, "#");
          String memberName = null;
          ClassDoc cd = null;
          if (st.countTokens() == 1) {
              //Case 2:  @value in same class.
              Doc holder = tag.holder();
              if (holder instanceof MemberDoc) {
                  cd = ((MemberDoc) holder).containingClass();
              } else if (holder instanceof ClassDoc) {
                  cd = (ClassDoc) holder;
              }
              memberName = st.nextToken();
          } else {
              //Case 3: @value in different class.
              cd = config.root.classNamed(st.nextToken());
              memberName = st.nextToken();
          }
          if (cd == null) {
              return null;
          }
          FieldDoc[] fields = cd.fields();
          for (int i = 0; i < fields.length; i++) {
              if (fields[i].name().equals(memberName)) {
                  return fields[i];
              }
          }
          return null;
      }
docs: Given the name of the field, return the corresponding FieldDoc. Return null
  due to invalid use of value tag if the name is null or empty string and if
  the value tag is not used on a field.
  
  @param config the current configuration of the doclet.
  @param tag the value tag.
  @param name the name of the field to search for.  The name should be in
  {@code <qualified class name>#<field name>} format. If the class name is omitted,
  it is assumed that the field is in the current class.
  
  @return the corresponding FieldDoc. If the name is null or empty string,
  return field that the value tag was used in. Return null if the name is null
  or empty string and if the value tag is not used on a field.