Add illustrative example of using requestedContextParameters property on ConditionContext.

Author: derekpierre

examples/taco/nodejs/src/index.ts

@@ -109,14 +109,21 @@ const decryptFromBytes = async (encryptedBytes: Uint8Array) => {
     domain: 'localhost',
     uri: 'http://localhost:3000',
   };
-  const authProvider = new EIP4361AuthProvider(
-    provider,
-    consumerSigner,
-    siweParams,
-  );
   const conditionContext =
     conditions.context.ConditionContext.fromMessageKit(messageKit);
-  conditionContext.addAuthProvider(USER_ADDRESS_PARAM_DEFAULT, authProvider);
+
+  // illustrative optional example of checking what context parameters are required
+  // unnecessary if you already know what the condition contains
+  if (
+    conditionContext.requestedContextParameters.has(USER_ADDRESS_PARAM_DEFAULT)
+  ) {
+    const authProvider = new EIP4361AuthProvider(
+      provider,
+      consumerSigner,
+      siweParams,
+    );
+    conditionContext.addAuthProvider(USER_ADDRESS_PARAM_DEFAULT, authProvider);
+  }
   return decrypt(provider, domain, messageKit, conditionContext);
 };