sdk/src/com/socialize/google/gdata/util/common/base/Preconditions.java
public static <T extends Iterable<?>> T checkContentsNotNull(T iterable,
      String errorMessageTemplate, Object... errorMessageArgs) {
    if (containsOrIsNull(iterable)) {
      throw new NullPointerException(
          format(errorMessageTemplate, errorMessageArgs));
    }
    return iterable;
  }
public static <T extends Iterable<?>> T checkContentsNotNull(T iterable,
      String errorMessageTemplate, Object... errorMessageArgs) {
    if (containsOrIsNull(iterable)) {
      throw new NullPointerException(
          format(errorMessageTemplate, errorMessageArgs));
    }
    return iterable;
  }
Ensures that an {@code Iterable} object passed as a parameter to the
calling method is not null and contains no null elements.

@param iterable the iterable to check the contents of
@param errorMessageTemplate a template for the exception message should the
check fail. The message is formed by replacing each {@code %s}
placeholder in the template with an argument. These are matched by
position - the first {@code %s} gets {@code errorMessageArgs[0]}, etc.
Unmatched arguments will be appended to the formatted message in square
braces. Unmatched placeholders will be left as-is.
@param errorMessageArgs the arguments to be substituted into the message
template. Arguments are converted to strings using
{@link String#valueOf(Object)}.
@return the non-null {@code iterable} reference just validated
@throws NullPointerException if {@code iterable} is null or contains at
least one null element