javagit/src/main/java/edu/nyu/cs/javagit/utilities/CheckUtilities.java
public static void checkNullListArgument(List<?> list, String variableName) {
    // TODO (jhl388): Write a unit test for this method.
    if (null == list) {
      throw new NullPointerException(ExceptionMessageMap.getMessage("000005")
          + "  { variableName=[" + variableName + "] }");
    }
    if (list.size() == 0) {
      throw new IllegalArgumentException(ExceptionMessageMap.getMessage("000005")
          + "  { variableName=[" + variableName + "] }");
    }
    for (int i = 0; i < list.size(); i++) {
      checkNullArgument(list.get(i), variableName);
    }
  }
public static void checkNullListArgument(List<?> list, String variableName) {
    // TODO (jhl388): Write a unit test for this method.
    if (null == list) {
      throw new NullPointerException(ExceptionMessageMap.getMessage("000005")
          + "  { variableName=[" + variableName + "] }");
    }
    if (list.size() == 0) {
      throw new IllegalArgumentException(ExceptionMessageMap.getMessage("000005")
          + "  { variableName=[" + variableName + "] }");
    }
    for (int i = 0; i < list.size(); i++) {
      checkNullArgument(list.get(i), variableName);
    }
  }
Checks a <code>List&lt;?&gt;</code> argument to make sure it is not null, has length > 0, and
none of its elements are null. If the <code>List&lt;?&gt;</code> or any contained instance is
null, a <code>NullPointerException</code> is thrown. If the <code>List&lt;?&gt;</code> or
any contained instance has length zero, an <code>IllegalArgumentException</code> is thrown.

@param list
The list to check.
@param variableName
The name of the variable being checked; for use in exception messages.