Fix incorrect mock implementation in tests that caused MissingMethodException to be thrown

Author: jyemin

driver-core/src/test/functional/com/mongodb/operation/ListCollectionsOperationSpecification.groovy

@@ -437,7 +437,7 @@ class ListCollectionsOperationSpecification extends OperationFunctionalSpecifica
 
         then:
         _ * connection.getDescription() >> helper.threeZeroConnectionDescription
-        1 * connection.commandAsync(helper.dbName, _, readPreference, _, _, _, _) >> { it[6].onResult(helper.commandResult, _) }
+        1 * connection.commandAsync(helper.dbName, _, readPreference, _, _, _, _) >> { it[6].onResult(helper.commandResult, null) }
 
         where:
         readPreference << [ReadPreference.primary(), ReadPreference.secondary()]

driver-core/src/test/functional/com/mongodb/operation/ListIndexesOperationSpecification.groovy

@@ -304,7 +304,7 @@ class ListIndexesOperationSpecification extends OperationFunctionalSpecification
 
         then:
         _ * connection.getDescription() >> helper.threeZeroConnectionDescription
-        1 * connection.commandAsync(helper.dbName, _, readPreference, _, _, _, _) >> { it[6].onResult(helper.commandResult, _) }
+        1 * connection.commandAsync(helper.dbName, _, readPreference, _, _, _, _) >> { it[6].onResult(helper.commandResult, null) }
 
         where:
         readPreference << [ReadPreference.primary(), ReadPreference.secondary()]