extractFile(ent.getKey(), embeddedFile, writer);
            }
        }
    }

    /**
     * Gets the embedded file from a file specification, trying different platform-specific variants.
     * @param fileSpec the file specification
     * @return the embedded file, or null if not found
     */
    protected PDEmbeddedFile getEmbeddedFile(final PDComplexFileSpecification fileSpec) {