VAPI-3164 Add <Refer> BXML verb support

src/main/java/com/bandwidth/sdk/model/bxml/Bxml.java

@@ -43,6 +43,7 @@ public class Bxml {
             @XmlElement(name = PlayAudio.TYPE_NAME, type = PlayAudio.class),
             @XmlElement(name = Record.TYPE_NAME, type = Record.class),
             @XmlElement(name = Redirect.TYPE_NAME, type = Redirect.class),
+            @XmlElement(name = Refer.TYPE_NAME, type = Refer.class),
             @XmlElement(name = ResumeRecording.TYPE_NAME, type = ResumeRecording.class),
             @XmlElement(name = Ring.TYPE_NAME, type = Ring.class),
             @XmlElement(name = SendDtmf.TYPE_NAME, type = SendDtmf.class),

src/main/java/com/bandwidth/sdk/model/bxml/Refer.java

@@ -0,0 +1,59 @@
+/**
+ * The {@code <Refer>} verb is used to initiate a SIP REFER on an existing call,
+ * instructing the remote SIP endpoint to contact a third party directly.
+ * On success the call is terminated — the remote endpoint redirects away from Bandwidth entirely.
+ */
+
+package com.bandwidth.sdk.model.bxml;
+
+import static com.bandwidth.sdk.model.bxml.utils.BxmlConstants.DEFAULT_CALLBACK_METHOD;
+
+import jakarta.xml.bind.annotation.XmlAccessType;
+import jakarta.xml.bind.annotation.XmlAccessorType;
+import jakarta.xml.bind.annotation.XmlAttribute;
+import jakarta.xml.bind.annotation.XmlElement;
+import jakarta.xml.bind.annotation.XmlType;
+import java.net.URI;
+
+import lombok.*;
+import lombok.Builder.Default;
+
+@XmlAccessorType(XmlAccessType.FIELD)
+@XmlType(name = Refer.TYPE_NAME)
+@Builder
+@NoArgsConstructor
+@AllArgsConstructor
+@Getter
+@EqualsAndHashCode
+/**
+ *
+ * @param sipUri (SipUri, required): The SIP URI to refer the call to. Must start with "sip:".
+ * @param referCompleteUrl (str, optional): URL to send the Refer Complete event to and request new BXML for failure recovery. May be a relative URL. Defaults to None.
+ * @param referCompleteMethod (str, optional): The HTTP method to use for the request to referCompleteUrl. GET or POST. Default value is POST.
+ * @param tag (str, optional): A custom string that will be sent with these and all future callbacks unless overwritten by a future tag attribute or cleared. May be cleared by setting tag="". Max length 256 characters. Defaults to None.
+ *
+ */
+public class Refer implements Verb {
+
+    public static final String TYPE_NAME = "Refer";
+
+    @XmlElement(name = "SipUri", type = SipUri.class)
+    @NonNull
+    protected SipUri sipUri;
+
+    @XmlAttribute
+    protected URI referCompleteUrl;
+
+    @XmlAttribute
+    @Default
+    protected String referCompleteMethod = DEFAULT_CALLBACK_METHOD;
+
+    @XmlAttribute
+    protected String tag;
+
+    @Override
+    public String getVerbName() {
+        return TYPE_NAME;
+    }
+}
+

src/test/java/com/bandwidth/sdk/unit/models/bxml/ReferVerbTest.java

@@ -0,0 +1,55 @@
+/**
+ *
+ * Unit tests for Refer Verb class
+ *
+ * @throws JAXBException if the test fails
+ */
+
+package com.bandwidth.sdk.unit.models.bxml;
+
+import com.bandwidth.sdk.model.bxml.Bxml;
+import com.bandwidth.sdk.model.bxml.Refer;
+import com.bandwidth.sdk.model.bxml.SipUri;
+
+import jakarta.xml.bind.JAXBContext;
+import jakarta.xml.bind.JAXBException;
+
+import org.junit.jupiter.api.Test;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
+
+import java.net.URI;
+
+public class ReferVerbTest {
+
+        SipUri sipUri = SipUri.builder()
+                .uri("sip:alice@atlanta.example.com")
+                .build();
+
+        Refer refer = Refer.builder()
+                        .sipUri(sipUri)
+                        .referCompleteUrl(URI.create("https://example.com/webhooks/refer_complete"))
+                        .referCompleteMethod("POST")
+                        .tag("test-tag")
+                        .build();
+
+        Refer referMinimal = Refer.builder()
+                        .sipUri(sipUri)
+                        .build();
+
+        @Test
+        public void referVerbWithAllAttributes() throws JAXBException {
+                JAXBContext jaxbContext = JAXBContext.newInstance(Bxml.class);
+                String expectedBxml = "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?><Bxml><Refer referCompleteUrl=\"https://example.com/webhooks/refer_complete\" referCompleteMethod=\"POST\" tag=\"test-tag\"><SipUri transferAnswerMethod=\"POST\" transferAnswerFallbackMethod=\"POST\" transferDisconnectMethod=\"POST\">sip:alice@atlanta.example.com</SipUri></Refer></Bxml>";
+                assertThat(new Bxml().with(refer).toBxml(jaxbContext), is(expectedBxml));
+        }
+
+        @Test
+        public void referVerbMinimal() throws JAXBException {
+                JAXBContext jaxbContext = JAXBContext.newInstance(Bxml.class);
+                String expectedBxml = "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?><Bxml><Refer referCompleteMethod=\"POST\"><SipUri transferAnswerMethod=\"POST\" transferAnswerFallbackMethod=\"POST\" transferDisconnectMethod=\"POST\">sip:alice@atlanta.example.com</SipUri></Refer></Bxml>";
+                assertThat(new Bxml().with(referMinimal).toBxml(jaxbContext), is(expectedBxml));
+        }
+}
+