void ensureContentLengthIsValid() { List<String> contentLengths = headers().getAll(CONTENT_LENGTH); checkArgument(contentLengths.size() <= 1, "Duplicate Content-Length found. %s", contentLengths); if (contentLengths.size() == 1) { checkArgument(isInteger(contentLengths.get(0)), "Invalid Content-Length found. %s", contentLengths.get(0)); } }