public String getRequiredParameter(String name) throws GuacamoleException {

        // Pull requested parameter, aborting if absent
        String value = getParameter(name);
        if (value == null)
            throw new GuacamoleClientException("Parameter \"" + name + "\" is required.");

        return value;

    }
Returns the value of the parameter having the given name, throwing an
exception if the parameter is missing.

@param name
    The name of the parameter to return.

@return
    The value of the parameter having the given name.

@throws GuacamoleException
    If the parameter is not present in the request.
guacamole/src/main/java/org/apache/guacamole/tunnel/TunnelRequest.java