Added externalTxId parameter and setter for externalTxId.

Added the value of externalTxId to transaction creation.

externalTxId will get one of:
- a string (singular usage, must be replaced after a use)
- a function that returns a string (used to generate random strings)
- undefined for no externalTxId

src/provider.ts

@@ -22,7 +22,7 @@ export class FireblocksWeb3Provider extends EthereumProvider {
   private chainId?: number;
   private feeLevel: FeeLevel;
   private note: string;
-  private externalTxId: string | undefined;
+  private externalTxId: (()=>string) | string | undefined;
   private accountsPopulatedPromise: Promise<void>;
   private pollingInterval: number;
   private oneTimeAddressesEnabled: boolean;
@@ -303,7 +303,7 @@ export class FireblocksWeb3Provider extends EthereumProvider {
       feeLevel: (isEip1559Fees || isLegacyFees) ? undefined : this.feeLevel,
       destination: this.getDestination(transaction.to),
       note: this.note,
-      externalTxId: this.externalTxId,
+      externalTxId: !this.externalTxId ? undefined  : (typeof this.externalTxId == 'function' ? this.externalTxId() : this.externalTxId),
       amount: formatEther(transaction.value?.toString() || "0"),
       extraParameters: transaction.data ? {
         contractCallData: transaction.data
@@ -354,7 +354,7 @@ export class FireblocksWeb3Provider extends EthereumProvider {
         id: vaultAccountId.toString(),
       },
       note: this.note,
-      externalTxId: this.externalTxId,
+      externalTxId: !this.externalTxId ? undefined  : (typeof this.externalTxId == 'function' ? this.externalTxId() : this.externalTxId),
       extraParameters: {
         rawMessageData: {
           messages: [message]
@@ -395,4 +395,8 @@ export class FireblocksWeb3Provider extends EthereumProvider {
   private getVaultAccountId(address: string): number {
     return parseInt(Object.entries(this.accounts).find(([id, addr]) => addr.toLowerCase() === address.toLowerCase())?.[0] || '');
   }
+
+  setExternalTxId(externalTxId: (()=>string) | string | undefined){
+    this.externalTxId = externalTxId;
+  }
 }

src/types.ts

@@ -47,5 +47,5 @@ export type FireblocksProviderConfig = {
   note?: string,
   pollingInterval?: number,
   oneTimeAddressesEnabled?: boolean,
-  externalTxId?: string,
+  externalTxId?: (() => string) | string,
 }