@Nonnull
	public static String insert(@Nonnull String text, int insertIndex, @Nullable String insertion) {
		if (insertion == null || insertion.isEmpty() || insertIndex < 0 || insertIndex > text.length()) return text;
		String pre = text.substring(0, insertIndex);
		String post = text.substring(insertIndex);
		return pre + insertion + post;
	}
@param text
		Input text.
@param insertIndex
		Position to insert into.
@param insertion
		Text to insert.

@return Modified text.
recaf-core/src/main/java/software/coley/recaf/util/StringUtil.java