Adds proxy information as capability in specified capabilities.

        :Args:
         - capabilities: The capabilities to which proxy will be added.

def add_to_capabilities(self, capabilities):
        """
        Adds proxy information as capability in specified capabilities.

        :Args:
         - capabilities: The capabilities to which proxy will be added.
        """
        proxy_caps = {}
        proxy_caps['proxyType'] = self.proxyType['string']
        if self.autodetect:
            proxy_caps['autodetect'] = self.autodetect
        if self.ftpProxy:
            proxy_caps['ftpProxy'] = self.ftpProxy
        if self.httpProxy:
            proxy_caps['httpProxy'] = self.httpProxy
        if self.proxyAutoconfigUrl:
            proxy_caps['proxyAutoconfigUrl'] = self.proxyAutoconfigUrl
        if self.sslProxy:
            proxy_caps['sslProxy'] = self.sslProxy
        if self.noProxy:
            proxy_caps['noProxy'] = self.noProxy
        if self.socksProxy:
            proxy_caps['socksProxy'] = self.socksProxy
        if self.socksUsername:
            proxy_caps['socksUsername'] = self.socksUsername
        if self.socksPassword:
            proxy_caps['socksPassword'] = self.socksPassword
        capabilities['proxy'] = proxy_caps