NullPointerException in PatternLayoutBase#caterForLegacyConverterMaps

[hisener]

With Logback 1.5.14+, we started getting NullPointerException in PatternLayoutBase. I don't have a reproducer right now, and we might be holding it wrong, but it looks like it is accessing a nullable field, so I thought I would report it.

java.lang.NullPointerException: 
	at ch.qos.logback.core.pattern.PatternLayoutBase.caterForLegacyConverterMaps(PatternLayoutBase.java:109)
	at ch.qos.logback.core.pattern.PatternLayoutBase.getEffectiveConverterMap(PatternLayoutBase.java:84)
	at ch.qos.logback.core.pattern.PatternLayoutBase.start(PatternLayoutBase.java:143)

This is related to d4804f9. PatternLayoutBase#caterForLegacyConverterMaps calls this.context.getObject.

logback/logback-core/src/main/java/ch/qos/logback/core/pattern/PatternLayoutBase.java

Lines 107 to 109 in 164754b

	private void caterForLegacyConverterMaps(Map<String, Supplier<DynamicConverter>> effectiveMap) {
	Map<String, String> mapFromContext = (Map<String, String>) this.context
	.getObject(CoreConstants.PATTERN_RULE_REGISTRY);

However, this.context is nullable. See also the null check after that #caterForLegacyConverterMaps method call

logback/logback-core/src/main/java/ch/qos/logback/core/pattern/PatternLayoutBase.java

Lines 84 to 88 in 164754b

	caterForLegacyConverterMaps(effectiveMap);
	// contextMap is more specific than the default map
	Context context = getContext();
	if (context != null) {