Fix option type parsing

- In `CommandRegistration` add `ResolvableType` for `OptionSpec` giving
  more spesific handling of a type.
- In `CommandParser` handle source and target types so that we
  have generics with `List`, `Set` and arrays working better.
- In `HandlerMethodArgumentResolver` add better handling for
  `ConversionService` for generic types.
- In `StandardMethodTargetRegistrar` add better types via `ResolvableType`
  now that `CommandRegistration` support it.
- In `OptionConversionCommands` remove converter from `String` to `Set` as
  now things should work as is if generic in a `Set` has a converter.
- Fixes #694

spring-shell-standard/src/main/java/org/springframework/shell/standard/StandardMethodTargetRegistrar.java

@@ -16,6 +16,7 @@
 package org.springframework.shell.standard;
 
 import java.lang.reflect.Method;
+import java.lang.reflect.Type;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
@@ -141,8 +142,9 @@ public class StandardMethodTargetRegistrar implements MethodTargetRegistrar, App
 						if (!longNames.isEmpty() || !shortNames.isEmpty()) {
 							log.debug("Registering longNames='{}' shortNames='{}'", longNames, shortNames);
 							Class<?> parameterType = mp.getParameterType();
+							Type genericParameterType = mp.getGenericParameterType();
 							OptionSpec optionSpec = builder.withOption()
-								.type(parameterType)
+								.type(genericParameterType)
 								.longNames(longNames.toArray(new String[0]))
 								.shortNames(shortNames.toArray(new Character[0]))
 								.position(mp.getParameterIndex())

spring-shell-standard/src/test/java/org/springframework/shell/standard/StandardMethodTargetRegistrarTests.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.
@@ -17,6 +17,7 @@
 package org.springframework.shell.standard;
 
 import java.util.Map;
+import java.util.Set;
 
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
@@ -500,4 +501,31 @@ public class StandardMethodTargetRegistrarTests {
 		public void foo1(@ShellOption("x") boolean arg1) {
 		}
 	}
+
+	@Test
+	void OptionWithCustomType() {
+		applicationContext = new AnnotationConfigApplicationContext(OptionWithCustomType.class);
+		registrar.setApplicationContext(applicationContext);
+		registrar.register(catalog);
+
+		assertThat(catalog.getRegistrations().get("foo1")).isNotNull();
+		assertThat(catalog.getRegistrations().get("foo1")).satisfies(reg -> {
+			assertThat(reg.getOptions().get(0)).satisfies(option -> {
+				assertThat(option.getType().getGeneric(0).getType()).isEqualTo(Pojo.class);
+			});
+		});
+
+	}
+
+	@ShellComponent
+	public static class OptionWithCustomType {
+
+		@ShellMethod(value = "foo1", prefix = "-")
+		public void foo1(@ShellOption Set<Pojo> arg1) {
+		}
+	}
+
+	public static class Pojo {
+
+	}
 }