message: IoTHub: update readme.java.md
diff: @@ -17,6 +17,7 @@ output-folder: $(azure-libraries-for-java-folder)/azure-mgmt-iothub
  ``` yaml $(java) && $(multiapi)
  batch:
  - tag: package-2020-03
  + - tag: package-preview-2019-07
  - tag: package-preview-2019-03
  - tag: package-2018-12-preview
  - tag: package-2018-04
  @@ -39,6 +40,19 @@ directive:
  to: PrivateLinkResource
  ```
  +### Tag: package-preview-2019-07
  +
  +These settings apply only when `--tag=package-preview-2019-07 --java` is specified on the command line.
  +Please also specify `--azure-libraries-for-java-folder=<path to the root directory of your azure-sdk-for-java clone>`.
  +
  +``` yaml $(tag) == 'package-preview-2019-07' && $(java) && $(multiapi)
  +java:
  + namespace: com.microsoft.azure.management.iothub.v2019_07_01_preview
  + output-folder: $(azure-libraries-for-java-folder)/sdk/iothub/mgmt-v2019_07_01_preview
  +regenerate-manager: true
  +generate-interface: true
  +```
  +
  ### Tag: package-preview-2019-03
  These settings apply only when `--tag=package-preview-2019-03 --java` is specified on the command line.
  