fix: exposeDefaultValues: false doesn't work in some cases

[acrosett]

Description

When using transform without a source specified, on an object that isn't a map, it will call the targetType constructor if present. Thus, newValue will contain all the default values of the targetType class. The option exposeDefaultValues doesn't change that behavior.

TransformOperationExecutor.ts line 151

      let newValue: any = source ? source : {};
      if (
        !source &&
        (this.transformationType === TransformationType.PLAIN_TO_CLASS ||
          this.transformationType === TransformationType.CLASS_TO_CLASS)
      ) {
        if (isMap) {
          newValue = new Map();
        } else if (targetType) {
          newValue = new (targetType as any)();
        } else {
          newValue = {};
        }
      }

TransformOperationExecutor.ts line L329

            if (subValue === undefined && this.options.exposeDefaultValues) {
              // Set default value if nothing provided
              finalValue = newValue[newValueKey];
            } else {

TransformOperationExecutor.ts line L360

          if (finalValue !== undefined || this.options.exposeUnsetFields) {
            if (newValue instanceof Map) {
              newValue.set(newValueKey, finalValue);
            } else {
              newValue[newValueKey] = finalValue;
            }
          }

TransformOperationExecutor.ts line 374

     return newValue;

Since newValue is returned L329 has no impact on the presence of default values.

Suggested fix

Check exposeDefaultValues when initializing newValue.

      let newValue: any = source ? source : {};
      if (
        !source &&
        (this.transformationType === TransformationType.PLAIN_TO_CLASS ||
          this.transformationType === TransformationType.CLASS_TO_CLASS)
      ) {
        if (isMap) {
          newValue = new Map();
        } else if (targetType && this.options.exposeDefaultValues) {
          newValue = new (targetType as any)();
        } else {
          newValue = {};
        }
      }

[ruscon]

I came across the same problem.
If specify transformation groups and property is not included in it, then the default value will be set for it