java.lang.UnsupportedOperationException
	at com.google.zetasql.ZetaSQLStrings.toIdentifierLiteral(ZetaSQLStrings.java:39)
	at com.google.zetasql.StructType.debugString(StructType.java:177)
	at com.google.zetasql.Type.toString(Type.java:334)
	at java.util.Formatter$FormatSpecifier.printString(Formatter.java:2886)
	at java.util.Formatter$FormatSpecifier.print(Formatter.java:2763)
	at java.util.Formatter.format(Formatter.java:2520)
	at java.util.Formatter.format(Formatter.java:2455)
	at java.lang.String.format(String.java:2942)