public PutOutcome put(final Txn<ByteBuffer> writeTxn,
                          final K key,
                          final V value,
                          final boolean overwriteExisting) {
        return put(writeTxn, key, value, overwriteExisting, false);
    }
@param writeTxn
@param key
@param value
@param overwriteExisting If true it will overwrite an existing entry with the same key. If false will
                         not do anything if an existing entry exists. If the database has
                         {@link DbiFlags#MDB_DUPSORT} set then you need to set this to true
                         to put multiple values for the same key.
@return
stroom-lmdb/src/main/java/stroom/lmdb/AbstractLmdbDb.java