resources/src/main/java/org/robolectric/res/android/DynamicRefTable.java
int addMapping(final String packageName, byte packageId) {
    Byte index = mEntries.get(packageName);
    if (index == null) {
      return UNKNOWN_ERROR;
    }
    mLookupTable[index] = packageId;
    return NO_ERROR;
  }
int addMapping(final String packageName, byte packageId) {
    Byte index = mEntries.get(packageName);
    if (index == null) {
      return UNKNOWN_ERROR;
    }
    mLookupTable[index] = packageId;
    return NO_ERROR;
  }
the given package.