PROTON-1925 Add enum values for know Section and DeliveryState

Allows for simpler identification and processing using switch or other
logic instead of instanceof checks for all types.
diff --git a/proton-j/src/main/java/org/apache/qpid/proton/amqp/messaging/Section.java b/proton-j/src/main/java/org/apache/qpid/proton/amqp/messaging/Section.java
index 2bcc4d5..8af3595 100644
--- a/proton-j/src/main/java/org/apache/qpid/proton/amqp/messaging/Section.java
+++ b/proton-j/src/main/java/org/apache/qpid/proton/amqp/messaging/Section.java
@@ -22,4 +22,16 @@
 
 public interface Section
 {
+    enum SectionType
+    {
+        AmqpSequence,
+        AmqpValue,
+        ApplicationProperties,
+        Data,
+        DeliveryAnnotations,
+        Footer,
+        Header,
+        MessageAnnotations,
+        Properties
+    }
 }
diff --git a/proton-j/src/main/java/org/apache/qpid/proton/amqp/transport/DeliveryState.java b/proton-j/src/main/java/org/apache/qpid/proton/amqp/transport/DeliveryState.java
index 4fa9806..4f3be66 100644
--- a/proton-j/src/main/java/org/apache/qpid/proton/amqp/transport/DeliveryState.java
+++ b/proton-j/src/main/java/org/apache/qpid/proton/amqp/transport/DeliveryState.java
@@ -29,5 +29,14 @@
  */
 public interface DeliveryState
 {
-
+    enum DeliveryStateType
+    {
+        Accepted,
+        Declared,
+        Modified,
+        Received,
+        Rejected,
+        Released,
+        Transactional
+    }
 }