public XMLWriter closeStartTag() {
        if (!inOpenStartTag) return this;
        w(GT);
        inOpenStartTag=false;
        return this;
    }
Closes the start tag. Usually, it is not necessary to call this, as the other methods in this will do
the right thing as needed. However, this can be called explicitly to allow content or subtags to be written
by a regular write call which bypasses the logic in this.
If a start tag is not currently open this has no effect.
vespajlib/src/main/java/com/yahoo/text/XMLWriter.java