Add @NotYetImplemented test with explanation

function-web/src/main/java/io/micronaut/function/web/AnnotatedFunctionRouteBuilder.java

@@ -79,7 +79,7 @@ public AnnotatedFunctionRouteBuilder(
         UriNamingStrategy uriNamingStrategy,
         ConversionService<?> conversionService,
         MediaTypeCodecRegistry codecRegistry,
-        @Value("${function.context-path:/}") String contextPath) {
+        @Value("${micronaut.function.context-path:/}") String contextPath) {
         super(executionHandleLocator, uriNamingStrategy, conversionService);
         this.localFunctionRegistry = new DefaultLocalFunctionRegistry(codecRegistry);
         this.contextPath = contextPath.endsWith("/") ? contextPath : contextPath + '/';

function-web/src/test/groovy/io/micronaut/function/web/JavaLambdaFunctionSpec.groovy

@@ -0,0 +1,27 @@
+package io.micronaut.function.web
+
+import io.micronaut.context.ApplicationContext
+import io.micronaut.http.HttpResponse
+import io.micronaut.http.HttpStatus
+import io.micronaut.http.client.RxHttpClient
+import io.micronaut.runtime.server.EmbeddedServer
+import spock.lang.Specification
+
+class JavaLambdaFunctionSpec extends Specification {
+
+    void "test string supplier"() {
+        given:
+        EmbeddedServer embeddedServer = ApplicationContext.run(EmbeddedServer)
+        RxHttpClient client = embeddedServer.applicationContext.createBean(RxHttpClient, embeddedServer.getURL())
+
+        when:
+        HttpResponse<String> response = client.toBlocking().exchange('/java/supplier/string', String)
+
+        then:
+        response.code() == HttpStatus.OK.code
+        response.body() == 'value'
+
+        cleanup:
+        embeddedServer.stop()
+    }
+}

function-web/src/test/groovy/io/micronaut/function/web/TestFunctionFactory.java

@@ -0,0 +1,15 @@
+package io.micronaut.function.web;
+
+import io.micronaut.context.annotation.Factory;
+import io.micronaut.function.FunctionBean;
+
+import java.util.function.Supplier;
+
+@Factory
+public class TestFunctionFactory {
+
+    @FunctionBean("java/supplier/string")
+    Supplier<String> get() {
+        return () -> "myvalue";
+    }
+}