service account fix on gcp_compute_instance
diff --git a/lib/ansible/modules/cloud/google/gcp_compute_instance.py b/lib/ansible/modules/cloud/google/gcp_compute_instance.py
index cb48c1deca1af0..b53a679dff40bd 100644
--- a/lib/ansible/modules/cloud/google/gcp_compute_instance.py
+++ b/lib/ansible/modules/cloud/google/gcp_compute_instance.py
@@ -319,7 +319,6 @@
                 description:
                     - Email address of the service account.
                 required: false
-                type: bool
             scopes:
                 description:
                     - The list of scopes to be made available for this service account.
@@ -862,7 +861,7 @@ def main():
                 preemptible=dict(type='bool')
             )),
             service_accounts=dict(type='list', elements='dict', options=dict(
-                email=dict(type='bool'),
+                email=dict(type='str'),
                 scopes=dict(type='list', elements='str')
             )),
             tags=dict(type='dict', options=dict(

##### SUMMARY
service account fix on gcp_compute_instance

<!--- If you are fixing an existing issue, please include "Fixes #nnn" in your
commit message and your description; but you should still explain what
the change does.-->

##### ISSUE TYPE
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 - Bugfix Pull Request

##### COMPONENT NAME
<!--- Name of the module, plugin, module or task -->
gcp_compute_instance

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes below -->
```
2.6
```


##### ADDITIONAL INFORMATION
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```

```
