public Map<String, String> getTokenMapping() throws GuacamoleException {

        // Get configuration file from GUACAMOLE_HOME
        File confFile = new File(environment.getGuacamoleHome(), tokenMappingFilename);
        if (!confFile.exists())
            return Collections.emptyMap();

        // Deserialize token mapping from YAML
        try {

            Map<String, String> mapping = mapper.readValue(confFile, new TypeReference<Map<String, String>>() {});
            if (mapping == null)
                return Collections.emptyMap();

            return mapping;

        }

        // Fail if YAML is invalid/unreadable
        catch (IOException e) {
            throw new GuacamoleServerException("Unable to read token mapping "
                    + "configuration file \"" + tokenMappingFilename + "\".", e);
        }

    }
Returns a mapping dictating the name of the secret which maps to each
parameter token. In the returned mapping, the value of each entry is the
name of the secret to use to populate the value of the parameter token,
and the key of each entry is the name of the parameter token which
should receive the value of the secret.

The name of the secret may contain its own tokens, which will be
substituted using values from the given filter. See the definition of
VaultUserContext for the names of these tokens and the contexts in which
they can be applied to secret names.

@return
    A mapping dictating the name of the secret which maps to each
    parameter token.

@throws GuacamoleException
    If the YAML file defining the token/secret mapping cannot be read.
extensions/guacamole-vault/modules/guacamole-vault-base/src/main/java/org/apache/guacamole/vault/conf/VaultConfigurationService.java