src/vs/platform/configuration/common/configurationModels.ts/ConfigurationModel/override
class ConfigurationModel:	override(identifier: string): ConfigurationModel {
		let overrideConfigurationModel = this.overrideConfigurations.get(identifier);
		if (!overrideConfigurationModel) {
			overrideConfigurationModel = this.createOverrideConfigurationModel(identifier);
			this.overrideConfigurations.set(identifier, overrideConfigurationModel);
		}
		return overrideConfigurationModel;
	}