anchor.diff:  pc.setLocation("com/mycompany/myprop.properties,com/mycompany/other.properties");
   ----
   
  +*Available as of Camel 2.19.0*
  +
  +You can set which location can be discarded if missing by by setting the ``optional`` attribute, which is false by default, i.e:
  +
  +[source,java]
  +----
  +pc.setLocations(
  +    "com/mycompany/override.properties;optional=true"
  +    "com/mycompany/defaults.properties");
  +----
  +
   [[Properties-Usingsystemandenvironmentvariablesinlocations]]
   Using system and environment variables in locations
   +++++++++++++++++++++++++++++++++++++++++++++++++++
  
positive.code:            xmlns:cm="http://aries.apache.org/blueprint/xmlns/blueprint-cm/v1.0.0"
             xsi:schemaLocation="
             http://www.osgi.org/xmlns/blueprint/v1.0.0 https://www.osgi.org/xmlns/blueprint/v1.0.0/blueprint.xsd">
   
      <!-- OSGI blueprint property placeholder -->
      <cm:property-placeholder id="myblueprint.placeholder" persistent-id="camel.blueprint">
          <!-- list some properties as needed -->
  
negative.code:             <cm:property name="prefix.result" value="mock:result"/>
          </cm:default-properties>
      </cm:property-placeholder>
  
      <camelContext xmlns="http://camel.apache.org/schema/blueprint">
          <!-- using Camel properties component and refer to the blueprint property placeholder by its id -->
          <propertyPlaceholder id="properties" location="blueprint:myblueprint.placeholder"
                               prefixToken="[[" suffixToken="]]"
                               propertyPrefix="prefix."/>
  
          <!-- in the route we can use {{ }} placeholders which will lookup in blueprint -->
          <route>
              <from uri="direct:start"/>
  