add logs and trace to developer guide

Author: rloutlaw

articles/azure-functions/functions-reference-java.md

@@ -88,7 +88,7 @@ with the corresponding `function.json`:
 
 Azure Functions supports the use of third-party libraries. By default, all dependencies specified in your project `pom.xml` file will be automatically bundled during the `mvn package` goal. For libraries not specified as dependencies in the `pom.xml` file, place them in a `lib` directory in the function's root directory. Dependencies placed in the `lib` directory will be added to the system class loader at runtime.
 
-## Data Types
+## Data type support
 
 You can use any data types in Java for the input and output data, including native types; customized Java types and specialized Azure types defined in `azure-functions-java-library` package. The Azure Functions runtime attempts convert the input received into the type requested by your code.
 
@@ -238,7 +238,7 @@ public class MyClass {
 
 Interact with Azure Functions execution environment via the `ExecutionContext` object defined in the `azure-functions-java-library` package. Use the `ExecutionContext` object to use invocation information and functions runtime information in your code.
 
-### Logging
+### Custom logging
 
 Access to the Functions runtime logger is available through the `ExecutionContext` object. This logger is tied to the Azure monitor and allows you to flag warnings and errors encountered during function execution.
 
@@ -259,6 +259,29 @@ public class Function {
 }
 ```
 
+## View logs and trace
+
+You can use the Azure CLI to stream Java standard out and error logging as well as other application logging. First, Configure your Function application to write application logging using the Azure CLI:
+
+```azurecli-interactive
+az webapp log config --name functionname --resource-group myResourceGroup --application-logging true
+```
+
+To stream logging output for your Function app using the Azure CLI, open a new command prompt, Bash, or Terminal session and enter the following command:
+
+```azurecli-interactive
+az webapp log tail --name webappname --resource-group myResourceGroup
+```
+The [az webapp log tail](/cli/azure/webapp/log) command has options to filter output using the `--provider` option. 
+
+To download the log files as a single ZIP file using the Azure CLI, open a new command prompt, Bash, or Terminal session and enter the following command:
+
+```azurecli-interactive
+az webapp log download --resource-group resourcegroupname --name functionappname
+```
+
+You must have enabled file system logging in the Azure Portal or Azure CLI before running this command.
+
 ## Environment variables
 
 Keep secret information such as keys or tokens out of your source code for security reasons. Use keys and tokens in your function code by reading them from environment variables.