public EndpointInfoBuilder fragment(String fragment) {
        requireNonNull(fragment, "fragment");
        checkState(regexPathPrefix == null, "fragment cannot be set with regexPathPrefix: %s", regexPathPrefix);
        this.fragment = fragment;
        return this;
    }
Sets the fragment of the {@code pathMapping}.
core/src/main/java/com/linecorp/armeria/server/docs/EndpointInfoBuilder.java