prohibit private constructors if they are not used in the class

[yegor256]

This code should be illegal:

class Foo {
  String s;
  public Foo(String s) {
    this.s = s;
  }
  private Foo(int x) { // this is wrong!
    // ...
  }
}

Instead, this private constructor should be public or protected or package visible.

[pnatashap]

@yegor256 are you sure about the example? this(1); should call private ctor in this case

[yegor256]

@pnatashap you are right, my mistake, I updated the example above