Prefix function names with spring-

* Add `spring-` prefix to function names

Fixes: #9

This commit renames each sub-module in the common, consumer, function
and supplier groups with a prefix of `spring-`.

* Update README.adoc links to new prefixed names

function/spring-payload-converter-function/src/test/java/functions/ByteArrayTextToStringTests.java

@@ -0,0 +1,79 @@
+/*
+ * Copyright 2020-2020 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 functions;
+
+import java.util.Collections;
+import java.util.function.Function;
+
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.messaging.Message;
+import org.springframework.messaging.MessageHeaders;
+import org.springframework.messaging.support.GenericMessage;
+import org.springframework.util.MimeTypeUtils;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class ByteArrayTextToStringTests {
+
+	private static final String MESSAGE = "hello world";
+	private static Function<Message<?>, Message<?>> converter;
+
+	@BeforeAll
+	static void before() {
+		converter = new ByteArrayTextToString();
+	}
+
+	@Test
+	public void testDefaultNoContentType() {
+		Message<?> converted = converter.apply(new GenericMessage<>(MESSAGE.getBytes()));
+		assertThat(converted).isNotNull().extracting(Message::getPayload).isEqualTo(MESSAGE);
+
+		converted = converter.apply(new GenericMessage<>(MESSAGE)); // String
+		assertThat(converted).isNotNull().extracting(Message::getPayload).isEqualTo(MESSAGE);
+	}
+
+	@Test
+	public void testApplicationJsonContentType() {
+		Message<?> converted = converter.apply(new GenericMessage<>(MESSAGE.getBytes(),
+				Collections.singletonMap(MessageHeaders.CONTENT_TYPE, MimeTypeUtils.APPLICATION_JSON_VALUE)));
+		assertThat(converted).isNotNull().extracting(Message::getPayload).isEqualTo("hello world");
+	}
+
+	@Test
+	public void testPlainTextContentType() {
+		Message<?> converted = converter.apply(new GenericMessage<>(MESSAGE.getBytes(),
+				Collections.singletonMap(MessageHeaders.CONTENT_TYPE, MimeTypeUtils.TEXT_PLAIN_VALUE)));
+		assertThat(converted).isNotNull().extracting(Message::getPayload).isEqualTo(MESSAGE);
+	}
+
+	@Test
+	public void testOctetContentType() {
+		Message<?> converted = converter.apply(new GenericMessage<>(MESSAGE.getBytes(),
+				Collections.singletonMap(MessageHeaders.CONTENT_TYPE, MimeTypeUtils.APPLICATION_OCTET_STREAM_VALUE)));
+		assertThat(converted).isNotNull().extracting(Message::getPayload).isEqualTo(MESSAGE.getBytes());
+	}
+
+	@Test
+	public void testRandomNonTextContentType() {
+		Message<?> converted = converter.apply(new GenericMessage<>(MESSAGE.getBytes(),
+				Collections.singletonMap(MessageHeaders.CONTENT_TYPE, "Random Content Type")));
+		assertThat(converted).isNotNull().extracting(Message::getPayload).isEqualTo(MESSAGE.getBytes());
+	}
+
+}