multiple configMap files in Helm

Question

Somehow I cannot load environment variables and I have the following error when the pod starts:

Error: Could not find or load main class
Caused by: java.lang.ClassNotFoundException:

The structure of my Helm chart:

I have the following configuration in the configmap.yaml Helm template:

apiVersion: v1
kind: ConfigMap
metadata:
  name: {{ .Values.nameOverride }}-config
data:
  application.yaml: {{ tpl (.Files.Get "files/application.yaml") . | quote }}
  appdynamicscontrollerconfig.yaml: {{ tpl (.Files.Get "files/appdynamics-controller-config.yaml") . | quote }}
  javaconfigmap.yaml: {{ tpl (.Files.Get "files/java-config-map.yaml") . | quote }}

The deployment.yaml Helm template:

      containers:
        - name: {{ .Values.nameOverride }}
          env:
            - name: APPLICATION
              valueFrom:
                configMapKeyRef:
                  name: {{ .Values.nameOverride }}-config
                  key: application.yaml
            - name: APPDYNAMICS_CONTROLLER_CONFIG
              valueFrom:
                configMapKeyRef:
                  name: {{ .Values.nameOverride }}-config
                  key: appdynamicscontrollerconfig.yaml
            - name: JAVA_OPTS
              valueFrom:
                configMapKeyRef:
                  name: {{ .Values.nameOverride }}-config
                  key: javaconfigmap.yaml

      volumes:
      - configMap:
          defaultMode: 420
          name: {{ .Values.nameOverride }}-config
          items:
            - key: application.yaml
              path: application.yaml
            - key: appdynamicscontrollerconfig.yaml
              path: appdynamics-controller-config.yaml
            - key: javaconfigmap.yaml
              path: java-config-map.yaml
        name: {{ .Values.nameOverride }}-config

          volumeMounts:
            - mountPath: /cs/app/config
              name: {{ .Values.nameOverride }}-config
              readOnly: true

Am I referencing incorrectly to the files which contain the environment variable? Probably yes, but I couldn't find a documentation for it.