feat(http): JsonMapper SAM in public package (no generic)

Author: thced

src/main/java/com/retailsvc/http/JsonMapper.java

@@ -0,0 +1,6 @@
+package com.retailsvc.http;
+
+@FunctionalInterface
+public interface JsonMapper {
+  Object mapFrom(byte[] body);
+}

src/test/java/com/retailsvc/http/JsonMapperTest.java

@@ -0,0 +1,13 @@
+package com.retailsvc.http;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.Test;
+
+class JsonMapperTest {
+  @Test
+  void usableAsLambda() {
+    JsonMapper m = body -> new String(body);
+    assertThat(m.mapFrom("hello".getBytes())).isEqualTo("hello");
+  }
+}