cactoos: TextEnvelope equals is not symmetric

https://github.com/yegor256/cactoos/blob/100885a4638555d30fb56beefbb6691108b30d0f/src/main/java/org/cactoos/text/TextEnvelope.java#L79-L90

From Java Object docs:

The equals method implements an equivalence relation on non-null object references:

It is reflexive: for any non-null reference value x, x.equals(x) should return true. It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true. It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true. It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified. For any non-null reference value x, x.equals(null) should return false.

But TextEnvelope equals() implementation is not symmetric:

class Env extends TextEnvelope {
  public Env(String str) {
    super(new TextOf(str));
  }
}

class Txt implements Text {
  private final String str;
  public Txt(final String str) {
    this.str = str;
  }
  @Override
  public String asString() {
    return this.str;
  }
}

final String str = "test";
Text env = new Env(str)
Text txt = new Txt(str)
env.equals(txt) // returns true
txt.equals(env) // returns false