Make use of custom types configurable in YamlProcessor

[sbrannen]

Overview

Since SnakeYaml allows for custom types to be loaded when they are specified inside the YAML document, we should make it possible to configure the types that can be constructed.

Proposal

Provide a mechanism in YamlProcessor for configuring the supported custom types for the Yaml instance created in org.springframework.beans.factory.config.YamlProcessor.createYaml().

For example, a new void setSupportedCustomTypes(Class<?>... types) method could be added to YamlProcessor. If no supported types are configured, the Yaml instance would be created as it is currently, without any restrictions. If supported types have been configured, the Yaml instance would be created with restrictions in place. The TypeLimitedConstructor recently introduced in Spring Boot can serve as inspiration for the latter.

Related Issues

• Restrict use of custom YAML types spring-boot#21596