public static String resolveConfIndirection(String valInConf)
      throws IOException {
    if (valInConf == null) return null;
    if (!valInConf.startsWith("@")) {
      return valInConf;
    }
    String path = valInConf.substring(1).trim();
    return Files.asCharSource(new File(path), StandardCharsets.UTF_8).read().trim();
  }
@Test
  public void testConfIndirection() throws IOException {
    assertNull(ZKUtil.resolveConfIndirection(null));
    assertEquals("x", ZKUtil.resolveConfIndirection("x"));
    
    TEST_FILE.getParentFile().mkdirs();
    Files.asCharSink(TEST_FILE, StandardCharsets.UTF_8).write("hello world");
    assertEquals("hello world", ZKUtil.resolveConfIndirection(
        "@" + TEST_FILE.getAbsolutePath()));
    
    try {
      ZKUtil.resolveConfIndirection("@" + BOGUS_FILE);
      fail("Did not throw for non-existent file reference");
    } catch (FileNotFoundException fnfe) {
      assertTrue(fnfe.getMessage().startsWith(BOGUS_FILE));
    }
  }