added jaxb adapter for instant objects

scm-core/src/main/java/sonia/scm/xml/XmlInstantAdapter.java

@@ -0,0 +1,25 @@
+package sonia.scm.xml;
+
+import javax.xml.bind.annotation.adapters.XmlAdapter;
+import java.time.Instant;
+import java.time.format.DateTimeFormatter;
+import java.time.temporal.TemporalAccessor;
+
+/**
+ * JAXB adapter for {@link Instant} objects.
+ *
+ * @since 2.0.0
+ */
+public class XmlInstantAdapter extends XmlAdapter<String, Instant> {
+
+  @Override
+  public String marshal(Instant instant) {
+    return DateTimeFormatter.ISO_INSTANT.format(instant);
+  }
+
+  @Override
+  public Instant unmarshal(String text) {
+    TemporalAccessor parsed = DateTimeFormatter.ISO_INSTANT.parse(text);
+    return Instant.from(parsed);
+  }
+}

scm-core/src/test/java/sonia/scm/xml/XmlInstantAdapterTest.java

@@ -0,0 +1,47 @@
+package sonia.scm.xml;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.junitpioneer.jupiter.TempDirectory;
+
+import javax.xml.bind.JAXB;
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import javax.xml.bind.annotation.XmlRootElement;
+import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
+import java.nio.file.Path;
+import java.time.Instant;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+@ExtendWith(TempDirectory.class)
+class XmlInstantAdapterTest {
+
+  @Test
+  void shouldMarshalAndUnmarshalInstant(@TempDirectory.TempDir Path tempDirectory) {
+    Path path = tempDirectory.resolve("instant.xml");
+
+    Instant instant = Instant.now();
+    InstantObject object = new InstantObject(instant);
+    JAXB.marshal(object, path.toFile());
+
+    InstantObject unmarshaled = JAXB.unmarshal(path.toFile(), InstantObject.class);
+    assertEquals(instant, unmarshaled.instant);
+  }
+
+  @XmlRootElement(name = "instant-object")
+  @XmlAccessorType(XmlAccessType.FIELD)
+  public static class InstantObject {
+
+    @XmlJavaTypeAdapter(XmlInstantAdapter.class)
+    private Instant instant;
+
+    public InstantObject() {
+    }
+
+    InstantObject(Instant instant) {
+      this.instant = instant;
+    }
+  }
+
+}