class NullStringSerialize extends TypeAdapter<String> {

    @Override
    public void write(JsonWriter out, String s) throws IOException {<FILL_FUNCTION_BODY>}

    @Override
    public String read(JsonReader jsonReader) throws IOException {
        return TypeAdapters.STRING.read(jsonReader);
    }
}

        if (s == null) {
            out.value("");
        } else {
            out.value(s);
        }
    
<methods>public void <init>() ,public final java.lang.String fromJson(java.io.Reader) throws java.io.IOException,public final java.lang.String fromJson(java.lang.String) throws java.io.IOException,public final java.lang.String fromJsonTree(com.google.gson.JsonElement) ,public final TypeAdapter<java.lang.String> nullSafe() ,public abstract java.lang.String read(com.google.gson.stream.JsonReader) throws java.io.IOException,public final java.lang.String toJson(java.lang.String) ,public final void toJson(java.io.Writer, java.lang.String) throws java.io.IOException,public final com.google.gson.JsonElement toJsonTree(java.lang.String) ,public abstract void write(com.google.gson.stream.JsonWriter, java.lang.String) throws java.io.IOException<variables>