@Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        JRTConnection that = (JRTConnection) o;
        return address.equals(that.address);
    }
This is synchronized to avoid multiple ConfigInstances creating new targets simultaneously, if
the existing target is null, invalid or has not yet been initialized.

@return The existing target, or a new one if invalid or null.
config/src/main/java/com/yahoo/vespa/config/JRTConnection.java