anchor.diff:  quarkus.datasource.url=jdbc:mysql://remotehost:3306/mydatabase?useSSL=false
   ----
   
  -can be simplified by having
  +can be simplified by having:
   
   [source,properties]
   ----
  
positive.code: Using `@ConfigProperty("quarkus.profile")` will *not* work properly.
  ====
  
  === Using placeholders
  
  Quarkus supports the use of placeholders in the `application.properties` file on build time.
  
  The placeholder can be used by enclosing the key inside `${}`.
  
  For example having the following property:
  
  [source,properties]
  ----
  remote.host=quarkus.io
  ----
  having another property defined as
  
  [source,properties]
  ----
  callable.url=http://${remote.host}/
  ----
  
  will result on the value of the `callable.url` property to be set at build time to
  
  [source,properties]
  ----
  callable.url=quarkus.io
  ----
  
  Another example would be defining different database servers depending on profiles used
  
  [source,properties]
  ----
  
negative.code: quarkus.datasource.url=jdbc:mysql://${application.server}:3306/mydatabase?useSSL=false
  ----
  
  It does result in one more line in this example but the value of `application.server` can be reused in other properties,
  diminishing the possibility of typos and providing more flexibility in property definitions.
  
  === Combining Property Expressions and Environment Variables
  
  Quarkus also supports the combination of both property expressions and environment variables.
  
  Let's assume you have following property defined in `application.properties`:
  
  [source,properties]
  ----
  remote.host=quarkus.io
  ----
  
  You can combine environment variables and property expressions by having a property defined as follows:
  
  [source,properties]
  ----
  application.host=${HOST:${remote.host}}
  ----
  
  This will expand the `HOST` environment variable and use the value of the property `remote.host` as the default value if `HOST` is not set.
  
  For the purpose of this section we used the property `remote.host` we defined previously.
  It has to be noted that the value could have been a fixed one such as in:
  
  [source,properties]
  ----
  application.host=${HOST:localhost}
  ----
  
  which will result in `localhost` as the default value if `HOST` is not set.
  
  === Clearing properties
  
  