Created attachment 1142144 [details]
api_inconsistent_value_type.sh - reproducer script

Description of problem:
  API response to GET clusters/CLUSTERID/summary have inconsistent type of "storageusage". If there is no storage created in the cluster, it will return null. If there is some storage created in the cluster, it will return list.

Version-Release number of selected component (if applicable):
  rhscon-ceph-0.0.8-1.el7.x86_64
  rhscon-core-0.0.11-1.el7.x86_64
  rhscon-ui-0.0.25-1.el7.noarch

How reproducible:
  100%

Steps to Reproduce:
1. Install and configure USM cluster.
2. Accept few nodes and create ceph cluster.
3. Use api_inconsistent_value_type.sh script (in attachments) as reproducer (first parameter is USM server, second parameter is CLUSTERID), 
4. Check the value of "storageusage".
  # bash api_inconsistent_value_type.sh USM-SERVER CLUSTER-ID
5. Create storage in the cluster.
6. Check the value of "storageusage" (same as in step 4).

Actual results:
  In the step 4, it will return null:
    "storageusage":null
  In the step 6, it will return list:
    "storageusage":[{"name":"TestStorage01","usage":{"used":145,"total":12821381265,"percentused":1.130923392753503e-06}}]

Expected results:
  It should always return value in the same type. In this case, it should return empty list in step 4.

Additional info:
  If you have "jq" installed, you can uncomment line 13 in the api_inconsistent_value_type.sh script and it will print just the value of the storageusagve key.