This looks like a duplicate of the Basic Calculator kata.

nitpick: minor typo in the description indivi[DU]al

nitpicks: minor typos in the description

.. start compa[]ring from ..
.. also aster[OI]ds in ..

nitpick: minor typo in the description.

five thousand cups wi[T]hout being DEAD

A minor typo in the description:

... the 1st character of the ou[T]put is the average ...

I'd say drop maxTest from sample as it reveals the solution. Having testSimpleCases alone should be enough to start the challenge.

nitpick: a minor typo in the description damage rec[EI]ved

A few minor typos in the description:

• int[RE]preted => int[ER]preted
• respectiv[]ly => respectiv[E]ly

nitpick: a minor typo in the description the symbol[_]s in the top row.

nitpick: a minor typo in the description string conta[IN]ing.

nitpick: a minor typo in the description your succes[S]ful algorithm.

nitpick: a minor typo in the description are identical there[A]fter..

Shall we follow camel-case Java naming conventions here?

DiagonalProduct.[r]eturnProduct()

Any particular reason for using Boolean[] over primitive boolean[]?