Replace parser string joining with list

- Issue in #622 is that its command type is `String` and internally
  some incoming arguments(it's List) were converted to String by
  joining with space. This caused one case with help command to get
  conversion via spring's ConversionService(CollectionToStringConverter)
  which joins by commas. That was we saw in failed example.
- Remove needed joins in CommandParser and let it just pass List which
  then works better with ConversionService.
- This then needs a `command` option type change from String to String[]
  which it really is as you should be able to give whole command as
  an argument.
- Backport #622
- Fixes #623

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

@@ -261,7 +261,7 @@ public interface CommandParser {
 							}
 							if (pop != null && pop.option == null) {
 								if (!pop.args.isEmpty()) {
-									oargs.add(pop.args.stream().collect(Collectors.joining(" ")));
+									oargs.addAll(pop.args);
 								}
 							}
 						}
@@ -370,11 +370,7 @@ public interface CommandParser {
 					.filter(co -> co.getDefaultValue() != null)
 					.forEach(co -> {
 						Object value = co.getDefaultValue();
-						if (conversionService != null && co.getType() != null) {
-							if (conversionService.canConvert(co.getDefaultValue().getClass(), co.getType().getRawClass())) {
-								value = conversionService.convert(co.getDefaultValue(), co.getType().getRawClass());
-							}
-						}
+						value = convertOptionType(co, value);
 						results.add(ParserResult.of(co, Collections.emptyList(), value, null));
 					});
 				return ParserResults.of(results);
@@ -478,7 +474,7 @@ public interface CommandParser {
 						else {
 							if (arityMax > 0) {
 								int limit = Math.min(arguments.size(), arityMax);
-								value = arguments.stream().limit(limit).collect(Collectors.joining(" "));
+								value = arguments.stream().limit(limit).collect(Collectors.toList());
 								unmapped.addAll(arguments.subList(limit, arguments.size()));
 							}
 							else {

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

@@ -94,9 +94,9 @@ public class CommandParserTests extends AbstractCommandTests {
 		CommandParserResults results = parser.parse(options, args);
 		assertThat(results.results()).hasSize(2);
 		assertThat(results.results().get(0).option()).isSameAs(option1);
-		assertThat(results.results().get(0).value()).isEqualTo("foo1 foo2");
+		assertThat(results.results().get(0).value()).isEqualTo(Arrays.asList("foo1", "foo2"));
 		assertThat(results.results().get(1).option()).isSameAs(option2);
-		assertThat(results.results().get(1).value()).isEqualTo("bar1 bar2");
+		assertThat(results.results().get(1).value()).isEqualTo(Arrays.asList("bar1", "bar2"));
 		assertThat(results.positional()).isEmpty();
 	}
 
@@ -215,6 +215,18 @@ public class CommandParserTests extends AbstractCommandTests {
 		assertThat(results.positional()).containsExactly("value", "foo");
 	}
 
+	@Test
+	public void testMappedFromArgToString() {
+		CommandOption option1 = longOption("arg1", ResolvableType.forType(String.class), false, 0, 1, 2);
+		List<CommandOption> options = Arrays.asList(option1);
+		String[] args = new String[]{"--arg1", "value", "foo"};
+		CommandParserResults results = parser.parse(options, args);
+		assertThat(results.results()).hasSize(1);
+		assertThat(results.results().get(0).option()).isSameAs(option1);
+		assertThat(results.results().get(0).value()).isEqualTo("value,foo");
+		assertThat(results.positional()).isEmpty();
+	}
+
 	@Test
 	public void testShortOptionsCombined() {
 		CommandOption optionA = shortOption('a');
@@ -381,7 +393,7 @@ public class CommandParserTests extends AbstractCommandTests {
 		assertThat(results.results()).hasSize(2);
 		assertThat(results.results().get(0).option()).isSameAs(option1);
 		assertThat(results.results().get(1).option()).isSameAs(option2);
-		assertThat(results.results().get(0).value()).isEqualTo("1");
+		assertThat(results.results().get(0).value()).isEqualTo(Arrays.asList("1"));
 		// no type so we get raw list
 		assertThat(results.results().get(1).value()).isEqualTo(Arrays.asList("2"));
 	}

spring-shell-standard-commands/src/main/java/org/springframework/shell/standard/commands/Help.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2022 the original author or authors.
+ * Copyright 2017-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,6 +22,8 @@ import java.io.UncheckedIOException;
 import java.nio.charset.StandardCharsets;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import org.jline.utils.AttributedString;
 
@@ -75,13 +77,16 @@ public class Help extends AbstractShellComponent {
 	@ShellMethod(value = "Display help about available commands")
 	public AttributedString help(
 			@ShellOption(defaultValue = ShellOption.NULL, valueProvider = CommandValueProvider.class, value = { "-C",
-					"--command" }, help = "The command to obtain help for.", arity = Integer.MAX_VALUE) String command)
+					"--command" }, help = "The command to obtain help for.", arity = Integer.MAX_VALUE) String[] command)
 			throws IOException {
 		if (command == null) {
 			return renderCommands();
 		}
 		else {
-			return renderCommand(command);
+			String commandStr = Stream.of(command)
+				.map(c -> c.trim())
+				.collect(Collectors.joining(" "));
+			return renderCommand(commandStr);
 		}
 	}
 

spring-shell-standard-commands/src/test/java/org/springframework/shell/standard/commands/HelpTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2022 the original author or authors.
+ * Copyright 2022-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -121,7 +121,7 @@ public class HelpTests {
 				.and()
 			.build();
 		commandCatalog.register(registration);
-		String help = this.help.help("first-command").toString();
+		String help = this.help.help(new String[] { "first-command" }).toString();
 		help = removeNewLines(help);
 		assertThat(help).isEqualTo(sample());
 	}
@@ -146,7 +146,7 @@ public class HelpTests {
 	@Test
 	public void testUnknownCommand() throws Exception {
 		assertThatThrownBy(() -> {
-			this.help.help("some unknown command");
+			this.help.help(new String[] { "some", "unknown", "command" });
 		}).isInstanceOf(IllegalArgumentException.class);
 	}