private void writeEmbeddedFilePathData(int i, String fileId, Metadata mA, Metadata mB) {
        //container file, don't write anything
        if (i == 0) {
            return;
        }
        String pathA = null;
        String pathB = null;
        if (mA != null) {
            pathA = mA.get(TikaCoreProperties.EMBEDDED_RESOURCE_PATH);
        }
        if (mB != null) {
            pathB = mB.get(TikaCoreProperties.EMBEDDED_RESOURCE_PATH);
        }
        if (pathA != null) {
            Map<Cols, String> d = new HashMap<>();
            d.put(Cols.ID, fileId);
            d.put(Cols.EMBEDDED_FILE_PATH, pathA);
            try {
                writer.writeRow(EMBEDDED_FILE_PATH_TABLE_A, d);
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        if (pathB != null && (pathA == null || !pathA.equals(pathB))) {
            Map<Cols, String> d = new HashMap<>();
            d.put(Cols.ID, fileId);
            d.put(Cols.EMBEDDED_FILE_PATH, pathB);
            try {
                writer.writeRow(EMBEDDED_FILE_PATH_TABLE_B, d);
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
    }
Checks only the first item in each list. Returns the first
digest key shared by both, if it exists, null otherwise.

@param metadataListA
@param metadataListB
@return
tika-eval/tika-eval-app/src/main/java/org/apache/tika/eval/app/ExtractComparer.java