chore: linter fixes in supply chain example code

Signed-off-by: Peter Somogyvari <[email protected]>

Author: petermetz

examples/cactus-example-supply-chain-backend/src/main/typescript/infrastructure/supply-chain-app-dummy-infrastructure.ts

@@ -70,23 +70,23 @@ export class SupplyChainAppDummyInfrastructure {
   private _quorumAccount: Account | undefined;
   private _besuAccount: Account | undefined;
 
-  public get quorumAccount() {
+  public get quorumAccount(): Account {
     if (!this._quorumAccount) {
       throw new Error(`Must call deployContracts() first.`);
     } else {
       return this._quorumAccount;
     }
   }
 
-  public get besuAccount() {
+  public get besuAccount(): Account {
     if (!this._besuAccount) {
       throw new Error(`Must call deployContracts() first.`);
     } else {
       return this._besuAccount;
     }
   }
 
-  public get className() {
+  public get className(): string {
     return SupplyChainAppDummyInfrastructure.CLASS_NAME;
   }