Properly handle event payload members of blob and string type

aws/aws-event-streams/src/main/java/software/amazon/smithy/java/aws/events/AwsEventShapeDecoder.java

@@ -30,7 +30,7 @@
  * @param <E>  The type of the event
  * @param <IR> The type of the initial event
  */
-public final class AwsEventShapeDecoder<E extends SerializableStruct, IR extends SerializableStruct>
+final class AwsEventShapeDecoder<E extends SerializableStruct, IR extends SerializableStruct>
         implements EventDecoder<AwsEventFrame> {
 
     private final InitialEventType initialEventType;

aws/aws-event-streams/src/main/java/software/amazon/smithy/java/aws/events/EventHeaderSerializer.java

@@ -7,57 +7,55 @@
 
 import java.nio.ByteBuffer;
 import java.time.Instant;
-import java.util.Map;
-import software.amazon.eventstream.HeaderValue;
 import software.amazon.smithy.java.core.schema.Schema;
 import software.amazon.smithy.java.core.schema.SerializableStruct;
 import software.amazon.smithy.java.core.serde.SpecificShapeSerializer;
 
-public class EventHeaderSerializer extends SpecificShapeSerializer {
-    private final Map<String, HeaderValue> headers;
+class EventHeaderSerializer extends SpecificShapeSerializer {
+    private final HeadersBuilder headers;
 
-    public EventHeaderSerializer(Map<String, HeaderValue> headers) {
+    public EventHeaderSerializer(HeadersBuilder headers) {
         this.headers = headers;
     }
 
     @Override
     public void writeBoolean(Schema schema, boolean value) {
-        headers.put(schema.memberName(), HeaderValue.fromBoolean(value));
+        headers.put(schema.memberName(), value);
     }
 
     @Override
     public void writeShort(Schema schema, short value) {
-        headers.put(schema.memberName(), HeaderValue.fromShort(value));
+        headers.put(schema.memberName(), value);
     }
 
     @Override
     public void writeByte(Schema schema, byte value) {
-        headers.put(schema.memberName(), HeaderValue.fromByte(value));
+        headers.put(schema.memberName(), value);
     }
 
     @Override
     public void writeInteger(Schema schema, int value) {
-        headers.put(schema.memberName(), HeaderValue.fromInteger(value));
+        headers.put(schema.memberName(), value);
     }
 
     @Override
     public void writeLong(Schema schema, long value) {
-        headers.put(schema.memberName(), HeaderValue.fromLong(value));
+        headers.put(schema.memberName(), value);
     }
 
     @Override
     public void writeString(Schema schema, String value) {
-        headers.put(schema.memberName(), HeaderValue.fromString(value));
+        headers.put(schema.memberName(), value);
     }
 
     @Override
     public void writeBlob(Schema schema, ByteBuffer value) {
-        headers.put(schema.memberName(), HeaderValue.fromByteBuffer(value));
+        headers.put(schema.memberName(), value);
     }
 
     @Override
     public void writeTimestamp(Schema schema, Instant value) {
-        headers.put(schema.memberName(), HeaderValue.fromTimestamp(value));
+        headers.put(schema.memberName(), value);
     }
 
     @Override

aws/aws-event-streams/src/main/java/software/amazon/smithy/java/aws/events/HeadersBuilder.java

@@ -0,0 +1,179 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package software.amazon.smithy.java.aws.events;
+
+import java.nio.ByteBuffer;
+import java.time.Instant;
+import java.util.HashMap;
+import java.util.Map;
+import software.amazon.eventstream.HeaderValue;
+
+/**
+ * Util class to build headers for AWS events.
+ */
+final class HeadersBuilder {
+
+    private final Map<String, HeaderValue> headers = new HashMap<>();
+
+    HeadersBuilder() {}
+
+    /**
+     * Returns a headers builder for messages of type event.
+     */
+    static HeadersBuilder forEvent() {
+        return new HeadersBuilder()
+                .messageType(MessageType.EVENT);
+    }
+
+    /**
+     * Returns a headers builder for messages of type error.
+     */
+    static HeadersBuilder forError() {
+        return new HeadersBuilder()
+                .messageType(MessageType.ERROR);
+    }
+
+    /**
+     * Returns a headers builder for messages of type exception.
+     */
+    static HeadersBuilder forException() {
+        return new HeadersBuilder()
+                .messageType(MessageType.EXCEPTION);
+    }
+
+    public HeadersBuilder messageType(MessageType messageType) {
+        headers.put(":message-type", HeaderValue.fromString(messageType.toString()));
+        return this;
+    }
+
+    /**
+     * Sets the `:content-type` header.
+     */
+    public HeadersBuilder contentType(String contentType) {
+        headers.put(":content-type", HeaderValue.fromString(contentType));
+        return this;
+    }
+
+    /**
+     * Sets the `:event-type` header.
+     */
+    public HeadersBuilder eventType(String eventType) {
+        headers.put(":event-type", HeaderValue.fromString(eventType));
+        return this;
+    }
+
+    /**
+     * Sets the `:exception-type` header.
+     */
+    public HeadersBuilder exceptionType(String eventType) {
+        headers.put(":exception-type", HeaderValue.fromString(eventType));
+        return this;
+    }
+
+    /**
+     * Sets the `:error-code` header.
+     */
+    public HeadersBuilder errorCode(String errorCode) {
+        headers.put(":error-code", HeaderValue.fromString(errorCode));
+        return this;
+    }
+
+    /**
+     * Sets the `:error-message` header.
+     */
+    public HeadersBuilder errorMessage(String errorMessage) {
+        headers.put(":error-message", HeaderValue.fromString(errorMessage));
+        return this;
+    }
+
+    /**
+     * Adds the header with the given name and value.
+     */
+    public HeadersBuilder put(String name, String value) {
+        headers.put(name, HeaderValue.fromString(value));
+        return this;
+    }
+
+    /**
+     * Adds the header with the given name and value.
+     */
+    public HeadersBuilder put(String name, int value) {
+        headers.put(name, HeaderValue.fromInteger(value));
+        return this;
+    }
+
+    /**
+     * Adds the header with the given name and value.
+     */
+    public HeadersBuilder put(String name, long value) {
+        headers.put(name, HeaderValue.fromLong(value));
+        return this;
+    }
+
+    /**
+     * Adds the header with the given name and value.
+     */
+    public HeadersBuilder put(String name, boolean value) {
+        headers.put(name, HeaderValue.fromBoolean(value));
+        return this;
+    }
+
+    /**
+     * Adds the header with the given name and value.
+     */
+    public HeadersBuilder put(String name, short value) {
+        headers.put(name, HeaderValue.fromShort(value));
+        return this;
+    }
+
+    /**
+     * Adds the header with the given name and value.
+     */
+    public HeadersBuilder put(String name, byte value) {
+        headers.put(name, HeaderValue.fromByte(value));
+        return this;
+    }
+
+    /**
+     * Adds the header with the given name and value.
+     */
+    public HeadersBuilder put(String name, ByteBuffer value) {
+        headers.put(name, HeaderValue.fromByteBuffer(value));
+        return this;
+    }
+
+    /**
+     * Adds the header with the given name and value.
+     */
+    public HeadersBuilder put(String name, Instant value) {
+        headers.put(name, HeaderValue.fromTimestamp(value));
+        return this;
+    }
+
+    /**
+     * Returns the map with the header values.
+     */
+    public Map<String, HeaderValue> build() {
+        return headers;
+    }
+
+    enum MessageType {
+        EVENT("event"),
+        ERROR("error"),
+        EXCEPTION("exception");
+
+        private final String value;
+
+        MessageType(String value) {
+            this.value = value;
+        }
+
+        @Override
+        public String toString() {
+            return value;
+        }
+    }
+}

aws/aws-event-streams/src/test/java/software/amazon/smithy/java/aws/events/AwsEventShapeDecoderTest.java

@@ -34,7 +34,7 @@ class AwsEventShapeDecoderTest {
     @Test
     public void testDecodeInitialResponse() {
         // Arrange
-        var headers = new AwsEventShapeEncoderTest.HeadersBuilder()
+        var headers = HeadersBuilder.forEvent()
                 .eventType("initial-response")
                 .contentType("text/json")
                 .put("intMemberHeader", 123)
@@ -57,7 +57,7 @@ public void testDecodeInitialResponse() {
     @Test
     public void testDecodeHeadersOnlyMember() {
         // Arrange
-        var headers = new AwsEventShapeEncoderTest.HeadersBuilder()
+        var headers = HeadersBuilder.forEvent()
                 .contentType("text/json")
                 .eventType("headersOnlyMember")
                 .put("sequenceNum", 123)
@@ -81,7 +81,7 @@ public void testDecodeHeadersOnlyMember() {
     @Test
     public void testDecodeStructureMember() {
         // Arrange
-        var headers = new AwsEventShapeEncoderTest.HeadersBuilder()
+        var headers = HeadersBuilder.forEvent()
                 .contentType("text/json")
                 .eventType("structureMember")
                 .build();
@@ -104,7 +104,7 @@ public void testDecodeStructureMember() {
     @Test
     public void testDecodeBodyAndHeaderMember() {
         // Arrange
-        var headers = new AwsEventShapeEncoderTest.HeadersBuilder()
+        var headers = HeadersBuilder.forEvent()
                 .contentType("text/json")
                 .eventType("bodyAndHeaderMember")
                 .put("intMember", 123)
@@ -131,7 +131,7 @@ public void testDecodeBodyAndHeaderMember() {
     @Test
     public void testDecodeStringMember() {
         // Arrange
-        var headers = new AwsEventShapeEncoderTest.HeadersBuilder()
+        var headers = HeadersBuilder.forEvent()
                 .contentType("text/json")
                 .eventType("stringMember")
                 .build();
@@ -154,9 +154,8 @@ public void testDecodeStringMember() {
     @Test
     public void testDecodeExceptionMember() {
         // Arrange
-        var headers = new AwsEventShapeEncoderTest.HeadersBuilder()
+        var headers = HeadersBuilder.forException()
                 .contentType("text/json")
-                .messageType("exception")
                 .exceptionType("modeledErrorMember")
                 .build();
         var message = new Message(headers, "{\"message\":\"Client exception\"}".getBytes(StandardCharsets.UTF_8));
@@ -179,8 +178,7 @@ public void testDecodeExceptionMember() {
     @Test
     public void testDecodeError() {
         // Arrange
-        var headers = new AwsEventShapeEncoderTest.HeadersBuilder()
-                .messageType("error")
+        var headers = HeadersBuilder.forError()
                 .put(":error-code", "InternalFailure")
                 .put(":error-message", "An internal server error occurred")
                 .build();