static void validateHttpResponseHeaderConfig(String config) {
        try {
            // validate format
            String[] configTokens = config.trim().split("\\s+", 2);
            if (configTokens.length != 2) {
                throw new ConfigException(String.format("Invalid format of header config '%s'. "
                        + "Expected: '[action] [header name]:[header value]'", config));
            }

            // validate action
            String method = configTokens[0].trim();
            validateHeaderConfigAction(method);

            // validate header name and header value pair
            String header = configTokens[1];
            String[] headerTokens = header.trim().split(":");
            if (headerTokens.length != 2) {
                throw new ConfigException(
                        String.format("Invalid format of header name and header value pair '%s'. "
                                + "Expected: '[header name]:[header value]'", header));
            }

            // validate header name
            String headerName = headerTokens[0].trim();
            if (headerName.isEmpty() || headerName.matches(".*\\s+.*")) {
                throw new ConfigException(String.format("Invalid header name '%s'. "
                        + "The '[header name]' cannot contain whitespace", headerName));
            }
        } catch (ArrayIndexOutOfBoundsException e) {
            throw new ConfigException(String.format("Invalid header config '%s'.", config), e);
        }
    }
Add the properties related to an internal-only server to the given {@link ConfigDef}.
@param configDef the {@link ConfigDef} to add the properties to; may not be null
connect/runtime/src/main/java/org/apache/kafka/connect/runtime/rest/RestServerConfig.java