annotation requires opt-in. Initializers Swift/Objective-C initializers are imported to Kotlin as constructors and factory methods named create . The latter happens with initializers declared in the Objective-C because Kotlin has no concept of extension constructors. Kotlin constructors are imported as initializers to Swift/Objective-C. Setters Writeable Objective-C properties overriding read-only properties as extensions. That's why these declarations can't be overridden in Kotlin. And the extension initializers aren't available as Kotlin constructors. Currently, there are two exceptions. Starting with Kotlin

at the start of a run but before any processing, except for the registration of listeners and initializers. 2. An ApplicationEnvironmentPreparedEvent is sent when the Environment to be used in the context necessary: server: port: 8000 spring: security: user: password: weak Spring profiles designated by using the spring.profiles element may optionally be negated by using the ! character. If both @SpringBootTest, as shown in the following example: @ContextConfiguration(classes = Config.class, initializers = ConfigFileApplicationContextInitializer.class) Note Using ConfigFileApplicationContextInitializer

at the start of a run but before any processing, except for the registration of listeners and initializers. 2. An ApplicationEnvironmentPreparedEvent is sent when the Environment to be used in the context necessary: server: port: 8000 spring: security: user: password: weak Spring profiles designated by using the spring.profiles element may optionally be negated by using the ! character. If both @SpringBootTest, as shown in the following example: @ContextConfiguration(classes = Config.class, initializers = ConfigFileApplicationContextInitializer.class) Note Using ConfigFileApplicationContextInitializer

at the start of a run but before any processing, except for the registration of listeners and initializers. 2. An ApplicationEnvironmentPreparedEvent is sent when the Environment to be used in the context necessary: server: port: 8000 spring: security: user: password: weak Spring profiles designated by using the spring.profiles element may optionally be negated by using the ! character. If both @SpringBootTest, as shown in the following example: @ContextConfiguration(classes = Config.class, initializers = ConfigFileApplicationContextInitializer.class) Note Using ConfigFileApplicationContextInitializer

at the start of a run but before any processing, except for the registration of listeners and initializers. 2. An ApplicationEnvironmentPreparedEvent is sent when the Environment to be used in the context necessary: server: port: 8000 spring: security: user: password: weak Spring profiles designated by using the spring.profiles element may optionally be negated by using the ! character. If both @SpringBootTest, as shown in the following example: @ContextConfiguration(classes = Config.class, initializers = ConfigFileApplicationContextInitializer.class) Note Using ConfigFileApplicationContextInitializer

at the start of a run but before any processing, except for the registration of listeners and initializers. 2. An ApplicationEnvironmentPreparedEvent is sent when the Environment to be used in the context necessary: server: port: 8000 spring: security: user: password: weak Spring profiles designated by using the spring.profiles element may optionally be negated by using the ! character. If both @SpringBootTest, as shown in the following example: @ContextConfiguration(classes = Config.class, initializers = ConfigFileApplicationContextInitializer.class) Note Using ConfigFileApplicationContextInitializer

at the start of a run but before any processing, except for the registration of listeners and initializers. 2. An ApplicationEnvironmentPreparedEvent is sent when the Environment to be used in the context necessary: server: port: 8000 spring: security: user: password: weak Spring profiles designated by using the spring.profiles element may optionally be negated by using the ! character. If both @SpringBootTest, as shown in the following example: @ContextConfiguration(classes = Config.class, initializers = ConfigFileApplicationContextInitializer.class) Note Using ConfigFileApplicationContextInitializer

at the start of a run but before any processing, except for the registration of listeners and initializers. 2. An ApplicationEnvironmentPreparedEvent is sent when the Environment to be used in the context necessary: server: port: 8000 spring: security: user: password: weak Spring profiles designated by using the spring.profiles element may optionally be negated by using the ! character. If both @SpringBootTest, as shown in the following example: @ContextConfiguration(classes = Config.class, initializers = ConfigFileApplicationContextInitializer.class) Note Using ConfigFileApplicationContextInitializer

at the start of a run but before any processing, except for the registration of listeners and initializers. 2. An ApplicationEnvironmentPreparedEvent is sent when the Environment to be used in the context necessary: server: port: 8000 spring: security: user: password: weak Spring profiles designated by using the spring.profiles element may optionally be negated by using the ! character. If both @SpringBootTest, as shown in the following example: @ContextConfiguration(classes = Config.class, initializers = ConfigFileApplicationContextInitializer.class) Note Using ConfigFileApplicationContextInitializer

at the start of a run but before any processing, except for the registration of listeners and initializers. 2. An ApplicationEnvironmentPreparedEvent is sent when the Environment to be used in the context necessary: server: port: 8000 spring: security: user: password: weak Spring profiles designated by using the spring.profiles element may optionally be negated by using the ! character. If both @SpringBootTest, as shown in the following example: @ContextConfiguration(classes = Config.class, initializers = ConfigFileApplicationContextInitializer.class) Note Using ConfigFileApplicationContextInitializer