Flink task manager failed for volume "hadoop-config-volume" with Flink Kubernetes Operator

I'm developing an application using Flink Kubernetes Operator version 1.1.0 but receiving the below error message in spawned taskmanager pods:

MountVolume.SetUp failed for volume "hadoop-config-volume" :  "hadoop-config-name" not found

Unable to attach or mount volumes: unmounted volumes=[hadoop-config-volume], unattached volumes=[hadoop-xml hadoop-config-volume flink-config-volume flink-token-kk558]: timed out waiting for the condition

My link app.yaml

      apiVersion: flink.apache.org/v1beta1
      kind: FlinkDeployment
      metadata: 
        name: "${DEPLOYMENT_NAME}"
        namespace: data
      spec: 
        flinkConfiguration:
          taskmanager.numberOfTaskSlots: "2"
        flinkVersion: v1_15
        image: "${IMAGE_TAG}"
        imagePullPolicy: Always
        job: 
          jarURI: local:///opt/flink/opt/executable.jar
          parallelism: 2
          state: running
          upgradeMode: stateless
        jobManager: 
          resource: 
            cpu: 1
            memory: 1024m
        podTemplate: 
          apiVersion: v1
          kind: Pod
          metadata: 
            namespace: bigdata
          spec: 
            containers:
              - 
                env:
                  -
                    name: HADOOP_CONF_DIR
                    value: /hadoop/conf
                envFrom: 
                  - 
                    configMapRef: 
                      name: data-connection
                name: flink-main-container
                volumeMounts: 
                  - 
                    mountPath: /hadoop/conf
                    name: hadoop-xml
            imagePullSecrets: 
              - 
                name: registry
            serviceAccount: flink
            volumes:
              - 
                configMap: 
                  name: hadoop-conf
                name: hadoop-xml
        serviceAccount: flink
        taskManager: 
          resource: 
            cpu: 2
            memory: 5000m

From the documentation, I believe hadoop-config-name is an internal configmap created by flink to ship hdfs configurations to taskmanager. I already mounted my configmap (contains *core-site.xml" and "hdfs-site.xml" to $HADOOP_CONF_DIR dir).

Is this a flink bug or I did something wrong with my set up?

For anyone facing the same issue, I fixed it by changing HADOOP_CONF_DIR -> HADOOP_CLASSPATH!