code: @Nonnull
    public T set(@Nonnull DocumentReference documentReference, @Nonnull Object pojo) {
      return set(documentReference, pojo, SetOptions.OVERWRITE);
    }
docs: Overwrites the document referred to by this DocumentReference. If the document doesn't exist
  yet, it will be created. If a document already exists, it will be overwritten.
  
  @param documentReference The DocumentReference to overwrite.
  @param pojo The POJO that will be used to populate the document contents.
  @return The instance for chaining.