GH-264 Added initial support for Supplier and Consumer for Azure

Resolves #264

spring-cloud-function-adapters/spring-cloud-function-adapter-azure/src/main/java/org/springframework/cloud/function/adapter/azure/AzureSpringBootRequestHandler.java

@@ -24,6 +24,7 @@ import com.microsoft.azure.functions.ExecutionContext;
 import com.microsoft.azure.functions.OutputBinding;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
 
 import org.springframework.cloud.function.context.AbstractSpringFunctionAdapterInitializer;
 
@@ -52,7 +53,8 @@ public class AzureSpringBootRequestHandler<I, O> extends AbstractSpringFunctionA
 			}
 			initialize(context);
 
-			Publisher<?> events = extract(convertEvent(input));
+			Publisher<?> events = input == null ? Mono.empty() : extract(convertEvent(input));
+
 			Publisher<?> output = apply(events);
 			return result(input, output);
 		}

spring-cloud-function-adapters/spring-cloud-function-adapter-azure/src/test/java/org/springframework/cloud/function/adapter/azure/AzureSpringBootRequestHandlerTests.java

@@ -19,7 +19,9 @@ package org.springframework.cloud.function.adapter.azure;
 import java.io.IOException;
 import java.util.Arrays;
 import java.util.List;
+import java.util.function.Consumer;
 import java.util.function.Function;
+import java.util.function.Supplier;
 import java.util.stream.Collectors;
 
 import com.microsoft.azure.functions.ExecutionContext;
@@ -120,6 +122,26 @@ public class AzureSpringBootRequestHandlerTests {
 		assertThat(bar).isNotNull();
 	}
 
+	@Test
+	public void supplierNonFluxBean() {
+		AzureSpringBootRequestHandler<Void, List<String>> handler = handler(NonFluxSupplierConfig.class);
+		List<String> result = handler.handleRequest(null, new TestExecutionContext("supplier"));
+
+		assertThat(result).isNotEmpty();
+		assertThat(result.toString()).isEqualTo("[foo1, foo2]");
+	}
+
+	private static String consumerResult;
+
+	@Test
+	public void consumerNonFluxBean() {
+		AzureSpringBootRequestHandler<String, Void> handler = handler(NonFluxConsumerConfig.class);
+		Object result = handler.handleRequest("foo1", new TestExecutionContext("consumer"));
+
+		assertThat(result).isNull();
+		assertThat(consumerResult).isEqualTo("foo1");
+	}
+
 	@After
 	public void close() throws IOException {
 		if (this.handler != null) {
@@ -137,6 +159,26 @@ public class AzureSpringBootRequestHandlerTests {
 
 	}
 
+	@Configuration
+	protected static class NonFluxSupplierConfig {
+
+		@Bean
+		public Supplier<List<String>> supplier() {
+			return () -> Arrays.asList("foo1", "foo2");
+		}
+
+	}
+
+	@Configuration
+	protected static class NonFluxConsumerConfig {
+
+		@Bean
+		public Consumer<String> consumer() {
+			return (v) -> consumerResult = v;
+		}
+
+	}
+
 	@Configuration
 	protected static class BareConfig {
 

spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/AbstractSpringFunctionAdapterInitializer.java

@@ -47,6 +47,7 @@ import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.support.GenericApplicationContext;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
+import org.springframework.util.CollectionUtils;
 
 /**
  * Base implementation for  adapter initializers and request handlers.
@@ -212,7 +213,7 @@ public abstract class AbstractSpringFunctionAdapterInitializer<C> implements Clo
 		}
 		@SuppressWarnings("unchecked")
 		O value = (O) result;
-		return value;
+		return CollectionUtils.isEmpty(result) ? null : value;
 	}
 
 	private boolean isSingleInput(Function<?, ?> function, Object input) {
@@ -332,7 +333,7 @@ public abstract class AbstractSpringFunctionAdapterInitializer<C> implements Clo
 
 		name = resolveName(Consumer.class, targetContext);
 		if (context.containsBean(name) && context.getBean(name) instanceof Consumer) {
-			this.consumer = getAndInstrumentFromContext(name);
+			this.function = getAndInstrumentFromContext(name); // FluxConsumer or any other consumer wrapper is a Function
 			return;
 		}