if (first) {
                    first = false;
                } else {
                    buf.append(',');
                }
                buf.append(escapeJson(entry.getKey())).append(':').append(escapeJson(entry.getValue()));
            }
            buf.append('}');
        } else if (obj instanceof Integer || obj instanceof Long || obj instanceof Float || obj instanceof Double) {

                    final Object obj = source.get(s);
                    if (obj instanceof Date) {
                        return false;
                    }
                    return !validateDateTimeString(source.get(s));
                }).collect(Collectors.toList()));
    }

    default boolean validateDateTimeString(final Object obj) {

    public boolean contains(@Nullable Object obj) {
      if (obj instanceof Set) {
        Set<?> set = (Set<?>) obj;
        return inputSet.keySet().containsAll(set);
      }
      return false;
    }

    @Override
    public boolean equals(@Nullable Object obj) {
      if (obj instanceof PowerSet) {
        PowerSet<?> that = (PowerSet<?>) obj;

  integrity sha512-41Cifkg6e8TylSpdtTpeLVMqvSBEVzTttHvERD741+pnZ8ANv0004MRL43QKPDlK9cGvNp6NZWZUBlbGXYxxng==

is-plain-obj@^2.1.0:
  version "2.1.0"
  resolved "https://registry.yarnpkg.com/is-plain-obj/-/is-plain-obj-2.1.0.tgz#45e42e37fccf1f40da8e5f76ee21515840c09287"
  integrity sha512-YWnfyRwxL/+SsrWYfOpUtz5b3YD+nyfkHvjbcanzk8zgyO4ASD67uVMRt8k5bM4lLMDnXfriRhOpemw+NfT1eA==

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