public <T> AsyncMutateInBuilder upsert(String path, T fragment) {
        if (StringUtil.isNullOrEmpty(path)) {
            throw new IllegalArgumentException("Path must not be empty for upsert");
        }
        this.mutationSpecs.add(new MutationSpec(Mutation.DICT_UPSERT, path, fragment));
        return this;
    }
public < T > AsyncMutateInBuilder upsert ( String path , T fragment ) { if ( StringUtil . isNullOrEmpty ( path ) ) { throw new IllegalArgumentException ( "Path must not be empty for upsert" ) ; } this . mutationSpecs . add ( new MutationSpec ( Mutation . DICT_UPSERT , path , fragment ) ) ; return this ; }
Insert a fragment, replacing the old value if the path exists.

@param path the path where to insert (or replace) a dictionary value.
@param fragment the new dictionary value to be applied.