public static ApplicationType fromString(String value) {
            return Stream.of(ApplicationType.values())
                    .filter(applicationType -> applicationType.type.equals(value))
                    .findFirst()
                    .orElse(DEFAULT);

        }
Create an application context from an application type, a parent producer and an id.

@param applicationType the application type
@param deployState the global deploy state for this model
@param parent the parent to be used for the config model
@param producerId the id to be used for the config model
@return a model context that can be passed to a model
config-model/src/main/java/com/yahoo/config/model/ConfigModelContext.java