@Override
    public String getCaption() {
        return caption;
    }
Constructor.

@param caption The caption of the completion (this is the left aligned autocompletion name on the left side of
               items in the dropdown box. If only a single completion is available in a context, then the caption
               will not be seen.
@param value   The text value of the completion. This does not need to be escaped.
@param meta    "meta" means the category of the substitution (this appears right aligned on the dropdown list).
               This is freeform description and can contain anything but typically a very short category
               description (9 chars or less) such as "function" or "param" or "template".
@param tooltip "tooltip" is an escaped html tooltip to be displayed when the completion option is displayed, this
               can be null.
@param score   The score is the value assigned to the autocompletion option. Scores with a higher value will
               appear closer to the top. Items with an identical score are sorted alphabetically by caption in
               the drop-down.
stroom-core-shared/src/main/java/stroom/query/shared/CompletionValue.java