Immutable @ConfigurationProperties

Question

Is it possible to have immutable (final) fields with Spring Boot\'s @ConfigurationProperties annotation? Example below

@ConfigurationProperties(         


        

Answer 1

From Spring Boot 2.2, it is at last possible to define an immutable class decorated with @ConfigurationProperties.
The documentation shows an example.
You just need to declare a constructor with the fields to bind (instead of the setter way) and to add the @ConstructorBinding annotation at the class level to indicate that constructor binding should be used.
So your actual code without any setter is now fine :

@ConstructorBinding
@ConfigurationProperties(prefix = "example")
public final class MyProps {

  private final String neededProperty;

  public MyProps(String neededProperty) {
    this.neededProperty = neededProperty;
  }

  public String getNeededProperty() { .. }
}