Defaults for older files are dependent on having loaded newer files

[eggrobin]

        System.err.println(
                IndexUnicodeProperties.make().getProperty(UcdProperty.Numeric_Type).getValue('1'));
        System.err.println(
                IndexUnicodeProperties.make(VersionInfo.UNICODE_4_1)
                        .getProperty(UcdProperty.Numeric_Type)
                        .getValue(0x2006));

correctly prints

Decimal
None

but the second statement alone,

        System.err.println(
                IndexUnicodeProperties.make(VersionInfo.UNICODE_4_1)
                        .getProperty(UcdProperty.Numeric_Type)
                        .getValue(0x2006));

prints null.

This is because we had no @missing lines in 4.1.0 and earlier, and we consider later @missing lines to be valid for earlier versions unless overriden with version suffixes in the Extra files, see

unicodetools/unicodetools/src/main/java/org/unicode/props/PropertyParsingInfo.java

Lines 2240 to 2262 in eac8de1

	private static void parseMissingFromValueAliases(Iterable<String> aliasesLines) {
	for (UcdLineParser.UcdLine line :
	new UcdLineParser(aliasesLines).withRange(false).withMissing(true)) {
	if (line.getType() == UcdLineParser.UcdLine.Contents.MISSING) {
	VersionInfo last_applicable_version = Settings.LATEST_VERSION_INFO;
	if (line.getParts().length > 3) {
	final String suffix = line.getParts()[3];
	if (!VERSION.matcher(suffix).matches()) {
	throw new IllegalArgumentException(
	"Expected version suffix, got " + suffix);
	}
	last_applicable_version = VersionInfo.getInstance(suffix.substring(1));
	}
	// # @missing: 0000..10FFFF; cjkIRG_KPSource; <none>
	setDefaultValueForPropertyName(
	line.getOriginalLine(),
	line.getParts()[1],
	line.getParts()[2],
	/* isEmpty= */ false,
	last_applicable_version);
	}
	}
	}

and

unicodetools/unicodetools/src/main/java/org/unicode/props/PropertyParsingInfo.java

Lines 566 to 571 in eac8de1

	public String getDefaultValue(VersionInfo version) {
	for (final var entry : defaultValues.entrySet()) {
	if (version.compareTo(entry.getKey()) <= 0) {
	return entry.getValue();
	}
	}

However, we do not actually ensure we load the files with the later @missing lines when reading older files…