public ConnectionConfig merge(final ConnectionConfig other) {
        if (other == null) {
            return this;
        } else {
            return new ConnectionConfig(
                    Objects.requireNonNullElse(other.className, className),
                    Objects.requireNonNullElse(other.url, url),
                    Objects.requireNonNullElse(other.user, user),
                    Objects.requireNonNullElse(other.password, password));
        }
    }
Merges the non-null values of other into this. If other is null return this.
stroom-config/stroom-config-common/src/main/java/stroom/config/common/ConnectionConfig.java