code: @Nonnull
    public EChange clearCachedSize (@Nullable final IReadableResource aRes)
    {
      if (aRes == null)
        return EChange.UNCHANGED;
  
      return m_aRWLock.writeLocked ( () -> {
        // Existing resource?
        if (m_aImageData.remove (aRes) != null)
          return EChange.CHANGED;
  
        // Non-existing resource?
        if (m_aNonExistingResources.remove (aRes))
          return EChange.CHANGED;
  
        return EChange.UNCHANGED;
      });
    }
docs: Remove a single resource from the cache.
  
  @param aRes
  The resource to be removed. May be <code>null</code>.
  @return Never <code>null</code>.