CommandRegistration should return same options

- Cache created CommandOption(s) to return same instance.
- Backport #648
- Fixes #649

Author: jvalkeal

spring-shell-core/src/main/java/org/springframework/shell/command/CommandRegistration.java

@@ -812,6 +812,7 @@ static class DefaultCommandRegistration implements CommandRegistration {
 		private String description;
 		private Supplier<Availability> availability;
 		private List<DefaultOptionSpec> optionSpecs;
+		private List<CommandOption> options;
 		private DefaultTargetSpec targetSpec;
 		private List<DefaultAliasSpec> aliasSpecs;
 		private DefaultExitCodeSpec exitCodeSpec;
@@ -857,11 +858,15 @@ public Availability getAvailability() {
 
 		@Override
 		public List<CommandOption> getOptions() {
-			return optionSpecs.stream()
+			if (options != null) {
+				return options;
+			}
+			options = optionSpecs.stream()
 				.map(o -> CommandOption.of(o.getLongNames(), o.getShortNames(), o.getDescription(), o.getType(),
 						o.isRequired(), o.getDefaultValue(), o.getPosition(), o.getArityMin(), o.getArityMax(),
 						o.getLabel(), o.getCompletion()))
 				.collect(Collectors.toList());
+			return options;
 		}
 
 		@Override

spring-shell-core/src/test/java/org/springframework/shell/command/CommandRegistrationTests.java

@@ -16,6 +16,7 @@
 package org.springframework.shell.command;
 
 import java.util.ArrayList;
+import java.util.List;
 
 import org.junit.jupiter.api.Test;
 
@@ -455,4 +456,20 @@ public void testOptionWithCompletion() {
 		assertThat(registration.getOptions()).hasSize(1);
 		assertThat(registration.getOptions().get(0).getCompletion()).isNotNull();
 	}
+
+	@Test
+	void optionShouldBeSameInstance() {
+		CommandRegistration registration = CommandRegistration.builder()
+				.command("command1")
+				.withOption()
+						.longNames("arg1")
+						.and()
+				.withTarget()
+						.consumer(ctx -> {})
+						.and()
+				.build();
+		List<CommandOption> options1 = registration.getOptions();
+		List<CommandOption> options2 = registration.getOptions();
+		assertThat(options1).isEqualTo(options2);
+	}
 }