anchor.diff:  When using Blueprint property placeholder in the Blueprint XML file, you
   can declare the properties directly in the XML file as shown below:
   
  +[source,xml]
  +----
  +<!-- blueprint property placeholders -->
  +<cm:property-placeholder persistent-id="my-placeholders" update-strategy="reload">
  +  <cm:default-properties>
  +    <cm:property name="greeting" value="Hello"/>
  +    <cm:property name="destination" value="mock:result"/>
  +  </cm:default-properties>
  +</cm:property-placeholder>
  +
  +<!-- a bean that uses a blueprint property placeholder -->
  +<bean id="myCoolBean" class="org.apache.camel.test.blueprint.MyCoolBean">
  +  <property name="say" value="${greeting}"/>
  +</bean>
  +
  +<camelContext xmlns="http://camel.apache.org/schema/blueprint">
  +
  +  <route>
  +    <from uri="direct:start"/>
  +    <bean ref="myCoolBean" method="saySomething"/>
  +    <to uri="{{destination}}"/>
  +  </route>
  +
  +</camelContext>
  +----
  +
  +
   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:
  +
  +[source,java]
  +----
  +protected String useOverridePropertiesWithConfigAdmin(Dictionary props) {
  +    // add the properties we want to override
  +    props.put("greeting", "Bye");
  +
  +    // return the PID of the config-admin we are using in the blueprint xml file
  +    return "my-placeholders";
  +}
  +----
  +
   
   To do this we override and implement the
   `useOverridePropertiesWithConfigAdmin` method. We can then put the
  
positive.code: 
  The example below has property placeholder in the `<jmxAgent>` tag:
  
  You can also define property placeholders in the various attributes on
  the `<camelContext>` tag such as `trace` as shown here:
  
  == Using JVM system properties or Environment variables as override or fallback values
  
  
negative.code: 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.
  