diff --git a/src/test/kotlin/org/opensearch/indexmanagement/indexstatemanagement/IndexStateManagementRestTestCase.kt b/src/test/kotlin/org/opensearch/indexmanagement/indexstatemanagement/IndexStateManagementRestTestCase.kt
index ab8e772a2..ddb510488 100644
--- a/src/test/kotlin/org/opensearch/indexmanagement/indexstatemanagement/IndexStateManagementRestTestCase.kt
+++ b/src/test/kotlin/org/opensearch/indexmanagement/indexstatemanagement/IndexStateManagementRestTestCase.kt
@@ -476,6 +476,8 @@ abstract class IndexStateManagementRestTestCase : IndexManagementRestTestCase()
 
     protected fun ExplainFilter.toHttpEntity(): HttpEntity = StringEntity(toJsonString(), APPLICATION_JSON)
 
+    protected fun ExplainFilter.toHttpEntity(): HttpEntity = StringEntity(toJsonString(), ContentType.APPLICATION_JSON)
+
     protected fun ChangePolicy.toHttpEntity(): HttpEntity {
         var string = "{\"${ChangePolicy.POLICY_ID_FIELD}\":\"$policyID\","
         if (state != null) {