added test case for Flow

src/test/java/io/github/jpmorganchase/fusion/model/FlowTest.java

@@ -0,0 +1,16 @@
+package io.github.jpmorganchase.fusion.model;
+
+import org.junit.jupiter.api.Test;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.is;
+
+public class FlowTest {
+
+    @Test
+    void constructionWithBuilderCorrectlyPopulatesAllFields() {
+        Flow flow = Flow.builder().flowDirection("The direction").build();
+        assertThat(flow.getFlowDirection(), is(equalTo("The direction")));
+    }
+}