fix: error serde (#372)

Author: kneekey23

AWSClientRuntime/Sources/HttpContextBuilder+Extension.swift

@@ -8,12 +8,12 @@
 import ClientRuntime
 
 extension HttpContext {
-    static let credentialsProvider = AttributeKey<AWSCredentialsProvider>(name: "AWSCredentialsProvider")
+    static let credentialsProvider = AttributeKey<CredentialsProvider>(name: "CredentialsProvider")
     static let region = AttributeKey<String>(name: "Region")
     static let signingName = AttributeKey<String>(name: "SigningName")
     static let signingRegion = AttributeKey<String>(name: "SigningRegion")
 
-    func getCredentialsProvider() -> AWSCredentialsProvider? {
+    func getCredentialsProvider() -> CredentialsProvider? {
         return attributes.get(key: HttpContext.credentialsProvider)
     }
 

AWSClientRuntime/Sources/Protocols/RestJSON/RestJSONError.swift

@@ -16,6 +16,9 @@ public struct RestJSONError {
 
     // returned by RESTFUL services that do no send a payload (like in a HEAD request)
     let X_AMZN_ERROR_MESSAGE_HEADER_NAME = "x-amzn-error-message"
+    
+    //returned by some services like Cognito
+    let X_AMZN_ERRORMESSAGE_HEADER_NAME = "x-amzn-ErrorMessage"
 
     // error message header returned by event stream errors
     let X_AMZN_EVENT_ERROR_MESSAGE_HEADER_NAME = ":error-message"
@@ -25,6 +28,10 @@ public struct RestJSONError {
         if message == nil {
             message = httpResponse.headers.value(for: X_AMZN_EVENT_ERROR_MESSAGE_HEADER_NAME)
         }
+        
+        if message == nil {
+            message = httpResponse.headers.value(for: X_AMZN_ERRORMESSAGE_HEADER_NAME)
+        }
 
         var type = httpResponse.headers.value(for: X_AMZN_ERROR_TYPE_HEADER_NAME)