/**
     * Get the value for the key 'app.extension.names'. <br>
     * The value is, e.g.  <br>
     * comment: Extension names for application customization.
     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */
    String getAppExtensionNames();

    /**
     * Get the value for the key 'app.extension.names' as {@link Integer}. <br>
     * The value is, e.g.  <br>

# Algorithm for digest calculation.
app.digest.algorism=sha256
# Regex pattern for properties to encrypt.
app.encrypt.property.pattern=.*password|.*key|.*token|.*secret

# Extension names for application customization.
app.extension.names=

# Audit log format.
app.audit.log.format=

# JVM options for the crawler process.
jvm.crawler.options=\
-Djava.awt.headless=true\n\
-Dfile.encoding=UTF-8\n\
-Djna.nosys=true\n\