get Or Put Internal
EN Non-inline core logic for getOrPut. Separated so that the public inline function does not need access to internal fields of ShardWrapper directly. This function is @PublishedApi, making it visible to the inlined call-sites.
PT Núcleo não-inline de getOrPut. Separado para evitar que a função inline pública precise de acesso direto aos campos internos de ShardWrapper.