Apply correct completion

- This commit fixes two issues.
- Firstly complete with correct option as existing bug was
  to wrongly always complete with first option which used
  wrong provider.
- Secondly filter out duplicate option proposals giving better
  result when options is already in place.
- Fixes #495

spring-shell-samples/src/main/java/org/springframework/shell/samples/e2e/InteractiveCompletionCommands.java

@@ -0,0 +1,106 @@
+/*
+ * 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.samples.e2e;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.shell.CompletionContext;
+import org.springframework.shell.CompletionProposal;
+import org.springframework.shell.command.CommandRegistration;
+import org.springframework.shell.standard.ShellComponent;
+import org.springframework.shell.standard.ShellMethod;
+import org.springframework.shell.standard.ShellOption;
+import org.springframework.shell.standard.ValueProvider;
+
+@ShellComponent
+public class InteractiveCompletionCommands extends BaseE2ECommands {
+
+	@ShellMethod(key = LEGACY_ANNO + "interactive-completion-1", group = GROUP)
+	public String testInteractiveCompletion1(
+		@ShellOption(valueProvider = Test1ValuesProvider.class) String arg1,
+		@ShellOption(valueProvider = Test2ValuesProvider.class) String arg2
+	) {
+		return "Hello " + arg1;
+	}
+
+	@Bean
+	CommandRegistration testInteractiveCompletion1Registration() {
+		Test1ValuesProvider test1ValuesProvider = new Test1ValuesProvider();
+		Test2ValuesProvider test2ValuesProvider = new Test2ValuesProvider();
+		return CommandRegistration.builder()
+			.command(REG, "interactive-completion-1")
+			.group(GROUP)
+			.withOption()
+				.longNames("arg1")
+				.completion(ctx -> test1ValuesProvider.complete(ctx))
+				.and()
+			.withOption()
+				.longNames("arg2")
+				.completion(ctx -> test2ValuesProvider.complete(ctx))
+				.and()
+			.withTarget()
+				.function(ctx -> {
+					String arg1 = ctx.getOptionValue("arg1");
+					return "Hello " + arg1;
+				})
+				.and()
+			.build();
+	}
+
+	@Bean
+	Test1ValuesProvider test1ValuesProvider() {
+		return new Test1ValuesProvider();
+	}
+
+	@Bean
+	Test2ValuesProvider test2ValuesProvider() {
+		return new Test2ValuesProvider();
+	}
+
+	static class Test1ValuesProvider implements ValueProvider {
+
+		private final static String[] VALUES = new String[] {
+			"values1Complete1",
+			"values1Complete2"
+		};
+
+		@Override
+		public List<CompletionProposal> complete(CompletionContext completionContext) {
+			return Arrays.stream(VALUES)
+				.map(CompletionProposal::new)
+				.collect(Collectors.toList());
+		}
+	}
+
+	static class Test2ValuesProvider implements ValueProvider {
+
+		private final static String[] VALUES = new String[] {
+			"values2Complete1",
+			"values2Complete2"
+		};
+
+		@Override
+		public List<CompletionProposal> complete(CompletionContext completionContext) {
+			return Arrays.stream(VALUES)
+				.map(CompletionProposal::new)
+				.collect(Collectors.toList());
+		}
+	}
+
+}