##### SUMMARY
Environment variables in plugin do not match Tower credential injector

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
lib/ansible/plugins/inventory/vmware_vm_inventory.py

##### ANSIBLE VERSION
```
ansible 2.8.0
  config file = /etc/ansible/ansible.cfg
  configured module search path = [u'/root/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python2.7/site-packages/ansible
  executable location = /bin/ansible
  python version = 2.7.5 (default, May 20 2019, 12:21:26) [GCC 4.8.5 20150623 (Red Hat 4.8.5-36)]
```
##### CONFIGURATION
```paste below

```

##### OS / ENVIRONMENT
Red Hat Enterprise Linux Server release 7.5

##### STEPS TO REPRODUCE
use vmware inventory plugin with vCenter credential in Ansible Tower
```yaml
---
plugin: vmware_vm_inventory
validate_certs: False
```


##### EXPECTED RESULTS
inventory should be parsed

##### ACTUAL RESULTS
```paste below
 [WARNING]:  * Failed to parse
/var/lib/awx/projects/_16__ansible_inventory/tests/vmware_vm_inventory.yaml
with auto plugin: No setting was provided for required configuration
plugin_type: inventory plugin: vmware_vm_inventory setting: username
```

#
#
from __future__ import (absolute_import, division, print_function)
__metaclass__ = type
DOCUMENTATION = '''
    name: vmware_vm_inventory
    plugin_type: inventory
    short_description: VMware Guest inventory source
    version_added: "2.7"
    author:
      - Abhijeet Kasurde (@Akasurde)
    description:
        - Get virtual machines as inventory hosts from VMware environment.
        - Uses any file which ends with vmware.yml or vmware.yaml as a YAML configuration file.
        - The inventory_hostname is always the 'Name' and UUID of the virtual machine. UUID is added as VMware allows virtual machines with the same name.
    extends_documentation_fragment:
      - inventory_cache
    requirements:
      - "Python >= 2.7"
      - "PyVmomi"
      - "requests >= 2.3"
      - "vSphere Automation SDK - For tag feature"
      - "vCloud Suite SDK - For tag feature"
    options:
        hostname: