* Used when LDAP authentication is enabled.
     */
    @Size(max = 1000)
    public String ldapProviderUrl;

    /**
     * LDAP security principal for binding to the LDAP server.
     * Used for authenticating with the LDAP server.
     */
    @Size(max = 1000)
    public String ldapSecurityPrincipal;

    /**
     * LDAP admin security principal for administrative operations.

search_engine.http.url=http://localhost:9201
# Path to SSL certificate authorities for secure HTTP connections.
search_engine.http.ssl.certificate_authorities=
# Username for authenticating to the search engine.
search_engine.username=
# Password for authenticating to the search engine.
search_engine.password=
# Interval (ms) for heartbeat checks to the search engine.
search_engine.heartbeat_interval=10000

     * comment: Username for authenticating to the search engine.
     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */
    String getSearchEngineUsername();

    /**
     * Get the value for the key 'search_engine.username' as {@link Integer}. <br>
     * The value is, e.g.  <br>
     * comment: Username for authenticating to the search engine.