anchor.diff:  Now if you want to unit test this blueprint XML file, then you can
   override the `loadConfigAdminConfigurationFile` and tell Camel which
   file to load as shown below:
  +
  +[source,java]
  +----
  +@Override
  +protected String[] loadConfigAdminConfigurationFile() {
  +    // String[0] = tell Camel the path of the .cfg file to use for OSGi ConfigAdmin in the blueprint XML file
  +    // String[1] = tell Camel the persistence-id of the cm:property-placeholder in the blueprint XML file
  +    return new String[]{"src/test/resources/etc/stuff.cfg", "stuff"};
  +}
  +----
  +
   
   Notice that this method requires to return a `String[]` with 2 values. The
   1st value is the path for the configuration file to load.
  
positive.code: When using Blueprint property placeholder in the Blueprint XML file, you
  can declare the properties directly in the XML file as shown below:
  
  Notice that we have a `<bean>` which refers to one of the properties. And
  in the Camel route we refer to the other using the `{{` and `}}` notation.
  
  Now if you want to override these Blueprint properties from an unit
  test, you can do this as shown below:
  
  To do this we override and implement the
  `useOverridePropertiesWithConfigAdmin` method. We can then put the
  
negative.code: 
  The example below has property placeholder in the `<jmxAgent>` tag:
  
  [source,xml]
  ----
  <camelContext xmlns="http://camel.apache.org/schema/spring">
      <propertyPlaceholder id="properties" location="org/apache/camel/spring/jmx.properties"/>
      <!-- we can use propery placeholders when we define the JMX agent -->
      <jmxAgent id="agent" registryPort="{{myjmx.port}}" disabled="{{myjmx.disabled}}"
                usePlatformMBeanServer="{{myjmx.usePlatform}}" createConnector="true"
                statisticsLevel="RoutesOnly" useHostIPAddress="true"/>
      <route id="foo" autoStartup="false">
          <from uri="seda:start"/>
          <to uri="mock:result"/>
      </route>
  </camelContext>
  ----
  
  
  You can also define property placeholders in the various attributes on
  the `<camelContext>` tag such as `trace` as shown here:
  
  [source,xml]
  ----
  <camelContext trace="{{foo.trace}}" xmlns="http://camel.apache.org/schema/spring">
      <propertyPlaceholder id="properties" location="org/apache/camel/spring/processor/myprop.properties"/>
      <template id="camelTemplate" defaultEndpoint="{{foo.cool}}"/>
      <route>
          <from uri="direct:start"/>
          <setHeader name="{{foo.header}}">
              <simple>${in.body} World!</simple>
          </setHeader>
          <to uri="mock:result"/>
      </route>
  </camelContext>
  ----
  
  
  == Using JVM system properties or Environment variables as override or fallback values
  
  