public File getPrivateKeyFile() throws GuacamoleException {
        return environment.getProperty(SAML_PRIVATE_KEY_PATH);
    }
Returns the file containing the private key to use when signing
requests to the SAML IdP. If the property is not set, null will be
returned.

@return
    The file containing the private key to use when signing
    requests to the SAML IdP, or null if not defined.

@throws GuacamoleException
    If the private key file cannot be parsed.
extensions/guacamole-auth-sso/modules/guacamole-auth-sso-saml/src/main/java/org/apache/guacamole/auth/saml/conf/ConfigurationService.java