static String format(String template, @Nullable Object... args) {
		template = String.valueOf(template); // null -> "null"

		// start substituting the arguments into the '%s' placeholders
		StringBuilder builder = new StringBuilder(template.length() + DEFAULT_16 * args.length);
		int templateStart = 0;
		int i = 0;
		while (i < args.length) {
			int placeholderStart = template.indexOf("%s", templateStart);
			if (placeholderStart == -1) {
				break;
			}
			builder.append(template, templateStart, placeholderStart);
			builder.append(args[i++]);
			templateStart = placeholderStart + 2;
		}
		builder.append(template.substring(templateStart));

		// if we run out of placeholders, append the extra args in square braces
		if (i < args.length) {
			builder.append(" [");
			builder.append(args[i++]);
			while (i < args.length) {
				builder.append(", ");
				builder.append(args[i++]);
			}
			builder.append(']');
		}

		return builder.toString();
	}
Substitutes each {@code %s} in {@code template} with an argument. These are matched by position - the first
{@code %s} gets {@code args[0]}, etc. If there are more arguments than placeholders, the unmatched arguments will
be appended to the end of the formatted message in square braces.

@param template a non-null string containing 0 or more {@code %s} placeholders.
@param args     the arguments to be substituted into the message template. Arguments are converted to strings using
                {@link String#valueOf(Object)}. Arguments can be null.
@return formatted message
ngrinder-core/src/main/java/org/ngrinder/common/util/Preconditions.java