fix: pluralize list response variables (#377)

Author: stainless-app[bot]

orb-java-core/src/test/kotlin/com/withorb/api/services/async/customers/CostServiceAsyncTest.kt

@@ -22,7 +22,7 @@ internal class CostServiceAsyncTest {
                 .build()
         val costServiceAsync = client.customers().costs()
 
-        val costFuture =
+        val costsFuture =
             costServiceAsync.list(
                 CustomerCostListParams.builder()
                     .customerId("customer_id")
@@ -33,8 +33,8 @@ internal class CostServiceAsyncTest {
                     .build()
             )
 
-        val cost = costFuture.get()
-        cost.validate()
+        val costs = costsFuture.get()
+        costs.validate()
     }
 
     @Test

orb-java-core/src/test/kotlin/com/withorb/api/services/blocking/customers/CostServiceTest.kt

@@ -22,7 +22,7 @@ internal class CostServiceTest {
                 .build()
         val costService = client.customers().costs()
 
-        val cost =
+        val costs =
             costService.list(
                 CustomerCostListParams.builder()
                     .customerId("customer_id")
@@ -33,7 +33,7 @@ internal class CostServiceTest {
                     .build()
             )
 
-        cost.validate()
+        costs.validate()
     }
 
     @Test