Anyone who uses open source software licensed under Apache 2.0 must include the following in their copy of the code, whether they have modified it or not:
1. The original copyright notice
2. A copy of the license itself
3. If applicable, a statement of any significant changes made to the original code
4. A copy of the NOTICE file with attribution notes (if the original library has one)
[...]
However, you do not need to release the modified code under Apache 2.0. Simply including any modification notifications is enough to comply with the license terms.
