[FAB-11976] hex encoding for binary keys in collection
[FAB-11976] hex encoding for binary keys in collection

Keys in a collection are hashed to binary and may contain unprintable
characters. This change set introduces hex encoding for said keys in order
to improve the usefulness of log entries.

Change-Id: I3bfcf63506cca968ca2d514c33bf5d20e4782e2a
Signed-off-by: Alessandro Sorniotti <f32b00f17cd31d4086a37e20e6815a9429f62787@sopit.net>
Signed-off-by: Matthias Neugschwandtner <e570e5dc4777cc7f93f0f6ac0d7f23388ed99ae3@zurich.ibm.com>

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