NPE in DefaultParamLabelRenderer.renderParameterLabel

[remkop]

When running Groovy CliBuilder tests with picocli 4.3.0, the following error occurs:

• CliBuilderTest.testAnnotationsInterfaceToStringWithName
• CliBuilderTest.testMandatoryParametersDoNotConsumeOtherOptions
• CliBuilderTest.testMultipleOccurrencesSeparateSeparate3
• CliBuilderTest.testLongOptionsRequireDoubleHyphenByDefault
• CliBuilderTest.testAcceptLongOptionsWithSingleHyphen_usage
• CliBuilderTest.testGroovyDocAntExample
• CliBuilderTest.testAnnotationsInterfaceToStringWithUsage

java.lang.NullPointerException
	at picocli.CommandLine$Help$DefaultParamLabelRenderer.renderParameterLabel(CommandLine.java:15041)
	at picocli.CommandLine$Help.createDetailedSynopsisOptionsText(CommandLine.java:14146)
	at picocli.CommandLine$Help.detailedSynopsis(CommandLine.java:14072)
	at picocli.CommandLine$Help.synopsis(CommandLine.java:14026)
	at picocli.CommandLine$Model$UsageMessageSpec$5.render(CommandLine.java:7209)
	at picocli.CommandLine.usage(CommandLine.java:2565)
	at picocli.CommandLine.usage(CommandLine.java:2543)
	at picocli.CommandLine.usage(CommandLine.java:2499)
	at picocli.CommandLine$usage.call(Unknown Source)
	at groovy.cli.picocli.CliBuilder.printUsage(CliBuilder.groovy:644)

The error occurs on this line:

String split = argSpec.splitRegexSynopsisLabel().isEmpty() ? argSpec.splitRegex() : argSpec.splitRegexSynopsisLabel();

which suggests that argSpec.splitRegexSynopsisLabel() returns null.

Looking at the ArgSpec constructor, this seems to be caused by a copy-and-paste bug:

// actual
splitRegex = builder.splitRegex == null ? "" : builder.splitRegex;
splitRegexSynopsisLabel = builder.splitRegex == null ? "" : builder.splitRegexSynopsisLabel;

Should be:

splitRegex = builder.splitRegex == null ? "" : builder.splitRegex;
splitRegexSynopsisLabel = builder.splitRegexSynopsisLabel== null ? "" : builder.splitRegexSynopsisLabel;