code: public final void unseal(Object sealKey)
      {
          if (sealKey == null) throw new IllegalArgumentException();
          if (this.sealKey != sealKey) throw new IllegalArgumentException();
          if (!sealed) throw new IllegalStateException();
          sealed = false;
          this.sealKey = null;
      }
docs: Unseal previously sealed Context object.
  The <tt>sealKey</tt> argument should not be null and should match
  <tt>sealKey</tt> suplied with the last call to
  {@link #seal(Object)} or an exception will be thrown.
  
  @see #isSealed()
  @see #seal(Object sealKey)