Support option label

- This adds `label` to `CommandOption` which is then used
  in a Help instead of type.
- Fixes #424

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

@@ -22,6 +22,7 @@ import java.util.stream.Stream;
 import org.springframework.shell.command.CommandOption;
 import org.springframework.shell.command.CommandRegistration;
 import org.springframework.util.ClassUtils;
+import org.springframework.util.StringUtils;
 
 /**
  * Model encapsulating info about {@code command}.
@@ -51,7 +52,7 @@ class CommandInfoModel {
 		List<CommandOption> options = registration.getOptions();
 		List<CommandParameterInfoModel> parameters = options.stream()
 			.map(o -> {
-				String type = o.getType() == null ? "String" : ClassUtils.getShortName(o.getType().getRawClass());
+				String type = commandOptionType(o);
 				List<String> arguments = Stream.concat(
 						Stream.of(o.getLongNames()).map(a -> "--" + a),
 						Stream.of(o.getShortNames()).map(s -> "-" + s))
@@ -67,6 +68,15 @@ class CommandInfoModel {
 		return new CommandInfoModel(name, description, parameters);
 	}
 
+	private static String commandOptionType(CommandOption o) {
+		if (StringUtils.hasText(o.getLabel())) {
+			return o.getLabel();
+		}
+		else {
+			return o.getType() == null ? "String" : ClassUtils.getShortName(o.getType().getRawClass());
+		}
+	}
+
 	public String getName() {
 		return name;
 	}