chore(signature-v4-multi-region): cleanups and docstrings

Author: siddsriv

packages/signature-v4-multi-region/package.json

@@ -24,7 +24,6 @@
     "@aws-sdk/types": "*",
     "@smithy/protocol-http": "^4.0.3",
     "@smithy/signature-v4": "^3.1.2",
-    "@smithy/signature-v4a": "*",
     "@smithy/types": "^3.3.0",
     "tslib": "^2.6.2"
   },

packages/signature-v4-multi-region/src/SignatureV4MultiRegion.ts

@@ -119,7 +119,7 @@ export class SignatureV4MultiRegion implements RequestPresigner, RequestSigner {
       } else {
         throw new Error(
           "Neither CRT nor JS SigV4a implementation is available. " +
-            "Please load either @aws-sdk/signature-v4-crt or @smithy/signature-v4a."
+          "Please load either @aws-sdk/signature-v4-crt or @smithy/signature-v4a."
         );
       }
     }

packages/signature-v4-multi-region/src/signature-v4a-container.ts

@@ -5,6 +5,12 @@ import type { HttpRequest, RequestPresigner, RequestSigner, RequestSigningArgume
  * @public
  */
 export type OptionalSigV4aSigner = {
+  /**
+   * This constructor is not typed so as not to require a type import
+   * from the signature-v4a package.
+   *
+   * The true type is SignatureV4a from @smithy/signature-v4a.
+   */
   new (options: any): RequestPresigner &
     RequestSigner & {
       signWithCredentials(
@@ -17,6 +23,11 @@ export type OptionalSigV4aSigner = {
 
 /**
  * @public
+ *
+ * \@smithy/signature-v4a will install the constructor in this
+ * container if it is installed.
+ *
+ * This avoids a runtime-require being interpreted statically by bundlers.
  */
 export const signatureV4aContainer: {
   SignatureV4a: null | OptionalSigV4aSigner;