CommandRegistration should return same options

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

Author: jvalkeal

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

@@ -1161,6 +1161,7 @@ static class DefaultCommandRegistration implements CommandRegistration {
 		private boolean hidden;
 		private String description;
 		private Supplier<Availability> availability;
+		private List<CommandOption> options;
 		private List<DefaultOptionSpec> optionSpecs;
 		private DefaultTargetSpec targetSpec;
 		private List<DefaultAliasSpec> aliasSpecs;
@@ -1218,7 +1219,10 @@ public Availability getAvailability() {
 
 		@Override
 		public List<CommandOption> getOptions() {
-			List<CommandOption> options = optionSpecs.stream()
+			if (options != null) {
+				return options;
+			}
+			options = optionSpecs.stream()
 				.map(o -> {
 					String[] longNames = o.getLongNames();
 					Function<String, String> modifier = o.getOptionNameModifier();

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;
 
@@ -600,4 +601,21 @@ void testOptionNameModifierFromDefault() {
 			assertThat(option.getLongNames()).isEqualTo(new String[] { "xarg1" });
 		});
 	}
+
+	@Test
+	void optionShouldBeSameInstance() {
+		CommandRegistration registration = CommandRegistration.builder()
+			.defaultOptionNameModifier(name -> "x" + name)
+			.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);
+	}
 }