sourceKey.indexTo(sourceDepth + 1);
int to = sourceKey.getIndex();
if (from >= 0 && to >= 0 && to > from) {
int newSize = targetKey.getEncodedSize() + to - from;
if(newSize > targetKey.getMaximumSize()) {
throw new StorageKeySizeExceededException(targetKey.getMaximumSize(), String.valueOf(descForError));
}
System.arraycopy(sourceKey.getEncodedBytes(), from,
targetKey.getEncodedBytes(), targetKey.getEncodedSize(), to - from);
targetKey.setEncodedSize(newSize);
}