Index cached data by method name

Index cached data by method name

Method.hashCode() is not a constant, whereas String.hashCode() is
pre-computed (for interned Strings). As Method.getName() is guaranteed
to be interned and getters have zero arguments, a method's name
is enough to uniquely identify the corresponding piece of data.

Therefore use Method.getName() to index cachedData.

Change-Id: Ie9fec477bd7346042e3700695588bc526fd56dac
JIRA: MDSAL-398
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>