Make ConversionService customisable

- Add ShellConversionServiceSupplier interface to define
  shell spesific ConversionService so that we don't
  get trouble with other services in boot.
- Fixes #435

spring-shell-autoconfigure/src/main/java/org/springframework/shell/boot/ParameterResolverAutoConfiguration.java

@@ -3,10 +3,8 @@ package org.springframework.shell.boot;
 import java.util.ArrayList;
 import java.util.List;
 
-import org.springframework.beans.factory.annotation.Qualifier;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
-import org.springframework.core.convert.ConversionService;
 import org.springframework.messaging.handler.annotation.support.HeadersMethodArgumentResolver;
 import org.springframework.messaging.handler.invocation.HandlerMethodArgumentResolver;
 import org.springframework.shell.command.ArgumentHeaderMethodArgumentResolver;
@@ -14,6 +12,7 @@ import org.springframework.shell.command.CommandContextMethodArgumentResolver;
 import org.springframework.shell.command.CommandExecution.CommandExecutionHandlerMethodArgumentResolvers;
 import org.springframework.shell.completion.CompletionResolver;
 import org.springframework.shell.completion.DefaultCompletionResolver;
+import org.springframework.shell.config.ShellConversionServiceSupplier;
 import org.springframework.shell.standard.ShellOptionMethodArgumentResolver;
 
 @Configuration(proxyBeanMethods = false)
@@ -26,12 +25,12 @@ public class ParameterResolverAutoConfiguration {
 
 	@Bean
 	public CommandExecutionHandlerMethodArgumentResolvers commandExecutionHandlerMethodArgumentResolvers(
-			@Qualifier("shellConversionService") ConversionService shellConversionService) {
+		ShellConversionServiceSupplier shellConversionServiceSupplier) {
 		List<HandlerMethodArgumentResolver> resolvers = new ArrayList<>();
-		resolvers.add(new ArgumentHeaderMethodArgumentResolver(shellConversionService, null));
+		resolvers.add(new ArgumentHeaderMethodArgumentResolver(shellConversionServiceSupplier.get(), null));
 		resolvers.add(new HeadersMethodArgumentResolver());
 		resolvers.add(new CommandContextMethodArgumentResolver());
-		resolvers.add(new ShellOptionMethodArgumentResolver(shellConversionService, null));
+		resolvers.add(new ShellOptionMethodArgumentResolver(shellConversionServiceSupplier.get(), null));
 		return new CommandExecutionHandlerMethodArgumentResolvers(resolvers);
 	}
 }

spring-shell-autoconfigure/src/main/java/org/springframework/shell/boot/SpringShellAutoConfiguration.java

@@ -20,20 +20,19 @@ import java.util.Set;
 
 import org.jline.terminal.Terminal;
 
-import org.springframework.beans.factory.annotation.Qualifier;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.convert.ApplicationConversionService;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
-import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.support.DefaultConversionService;
 import org.springframework.format.support.FormattingConversionService;
 import org.springframework.shell.ResultHandler;
 import org.springframework.shell.ResultHandlerService;
 import org.springframework.shell.Shell;
 import org.springframework.shell.command.CommandCatalog;
+import org.springframework.shell.config.ShellConversionServiceSupplier;
 import org.springframework.shell.context.ShellContext;
 import org.springframework.shell.exit.ExitCodeMappings;
 import org.springframework.shell.result.GenericResultHandlerService;
@@ -47,13 +46,13 @@ import org.springframework.shell.result.ResultHandlerConfig;
 public class SpringShellAutoConfiguration {
 
 	@Bean
-	@ConditionalOnMissingBean(value = ConversionService.class, name = { "shellConversionService" })
-	public ConversionService shellConversionService(ApplicationContext applicationContext) {
+	@ConditionalOnMissingBean
+	public ShellConversionServiceSupplier shellConversionServiceSupplier(ApplicationContext applicationContext) {
 		FormattingConversionService service = new FormattingConversionService();
 		DefaultConversionService.addDefaultConverters(service);
 		DefaultConversionService.addCollectionConverters(service);
 		ApplicationConversionService.addBeans(service, applicationContext);
-		return service;
+		return () -> service;
 	}
 
 	@Bean
@@ -67,10 +66,10 @@ public class SpringShellAutoConfiguration {
 
 	@Bean
 	public Shell shell(ResultHandlerService resultHandlerService, CommandCatalog commandRegistry, Terminal terminal,
-			@Qualifier("shellConversionService") ConversionService shellConversionService, ShellContext shellContext,
+			ShellConversionServiceSupplier shellConversionServiceSupplier, ShellContext shellContext,
 			ExitCodeMappings exitCodeMappings) {
 		Shell shell = new Shell(resultHandlerService, commandRegistry, terminal, shellContext, exitCodeMappings);
-		shell.setConversionService(shellConversionService);
+		shell.setConversionService(shellConversionServiceSupplier.get());
 		return shell;
 	}
 }

spring-shell-autoconfigure/src/test/java/org/springframework/shell/boot/ParameterResolverAutoConfigurationTests.java

@@ -21,10 +21,10 @@ import org.springframework.boot.autoconfigure.AutoConfigurations;
 import org.springframework.boot.test.context.runner.ApplicationContextRunner;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
-import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.support.DefaultConversionService;
 import org.springframework.shell.command.CommandExecution.CommandExecutionHandlerMethodArgumentResolvers;
 import org.springframework.shell.completion.CompletionResolver;
+import org.springframework.shell.config.ShellConversionServiceSupplier;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -49,31 +49,12 @@ public class ParameterResolverAutoConfigurationTests {
 				});
 	}
 
-	@Test
-	void multipleConversionServiceBeans() {
-		this.contextRunner
-				.withUserConfiguration(CustomShellConversionServiceConfiguration.class,
-						ExtraConversionServiceConfiguration.class)
-				.run((context) -> {
-					assertThat(context).hasSingleBean(CommandExecutionHandlerMethodArgumentResolvers.class);
-				});
-	}
-
 	@Configuration
 	static class CustomShellConversionServiceConfiguration {
 
 		@Bean
-		ConversionService shellConversionService() {
-			return new DefaultConversionService();
-		}
-	}
-
-	@Configuration
-	static class ExtraConversionServiceConfiguration {
-
-		@Bean
-		ConversionService conversionService() {
-			return new DefaultConversionService();
+		ShellConversionServiceSupplier shellConversionServiceSupplier() {
+			return () -> new DefaultConversionService();
 		}
 	}
 }

spring-shell-core/src/main/java/org/springframework/shell/config/ShellConversionServiceSupplier.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2022 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.shell.config;
+
+import java.util.function.Supplier;
+
+import org.springframework.core.convert.ConversionService;
+
+/**
+ * Interface to provide shell spesific {@link ConversionService}.
+ *
+ * @author Janne Valkealahti
+ */
+public interface ShellConversionServiceSupplier extends Supplier<ConversionService> {
+}