return oldValue;
      }
    }

    int valueHash = smearedHash(value);
    int valueEntry = findEntryByValue(value, valueHash);
    if (force) {
      if (valueEntry != ABSENT) {
        removeEntryValueHashKnown(valueEntry, valueHash);
      }
    } else {
      checkArgument(valueEntry == ABSENT, "Value already present: %s", value);
    }

    ensureCapacity(size + 1);
    keys[size] = key;