MicroProfile® Config 2.0 Release Review

This is the release for MP Config 2.0, with the following details.

A full list of changes delivered in the 2.0 release can be found at MicroProfile Config 2.0 Milestone.

Incompatible Changes

• ConfigSource#getPropertyNames is no longer a default method. The implementation of a ConfigSource must implement this method. (431)

• Previous versions of the specification would not evaluate Property Expressions. As such, previous working configuration may behave differently (if the used configuration contains values with Property Expressions syntax). Check the Property Expressions section on how to go back to the previous behaviour.

• Empty value or other special characters are no longer a valid config value for a particular return type. Refer to the earlier section of this spec for more details. In the previous release, the empty value was returned as an empty value. From now on, the empty value will cause NoSuchElementException to be thrown. (446) (531) (532) (397)

API/SPI Changes

• Convenience methods have been added to Config allowing for the retrieval of multi-valued properties as lists instead of arrays (#496)

• Enable bulk-extraction of config properties into a separate POJO by introducing @ConfigProperties (240)

• Enable users to determine the winning source for a configuration value (312) (43)

• Expose conversion mechanism in Config API (492)

• Add unwrap() methods to Config (84)

Functional Changes

• Support Configuration Profiles so that the corresponding properties associated with the active profile are used (#418)

• Provide built-in Converters: OptinalInt, OptionalLong and OptionalDouble (513)

• Clarifies that Converters for primitive wrappers apply to primitive types as well (520)

• Clarify that nulls cannot be passed in to Converters (542)

• Support Property Expressions: This provides a way to set and expand variables in property values (118)