src/share/classes/java/lang/Throwable.java

*** 451,463 ****
       *         been called on this throwable.
       * @since  1.4
       */
      public synchronized Throwable initCause(Throwable cause) {
          if (this.cause != this)
!             throw new IllegalStateException("Can't overwrite cause");
          if (cause == this)
!             throw new IllegalArgumentException("Self-causation not permitted");
          this.cause = cause;
          return this;
      }
  
      /**
--- 451,464 ----
       *         been called on this throwable.
       * @since  1.4
       */
      public synchronized Throwable initCause(Throwable cause) {
          if (this.cause != this)
!             throw new IllegalStateException("Can't overwrite cause with " +
!                                             Objects.toString(cause, "a null"), this);
          if (cause == this)
!             throw new IllegalArgumentException("Self-causation not permitted", this);
          this.cause = cause;
          return this;
      }
  
      /**
*** 1037,1047 ****
       * @throws NullPointerException if {@code exception} is {@code null}
       * @since 1.7
       */
      public final synchronized void addSuppressed(Throwable exception) {
          if (exception == this)
!             throw new IllegalArgumentException(SELF_SUPPRESSION_MESSAGE);
  
          if (exception == null)
              throw new NullPointerException(NULL_CAUSE_MESSAGE);
  
          if (suppressedExceptions == null) // Suppressed exceptions not recorded
--- 1038,1048 ----
       * @throws NullPointerException if {@code exception} is {@code null}
       * @since 1.7
       */
      public final synchronized void addSuppressed(Throwable exception) {
          if (exception == this)
!             throw new IllegalArgumentException(SELF_SUPPRESSION_MESSAGE, exception);
  
          if (exception == null)
              throw new NullPointerException(NULL_CAUSE_MESSAGE);
  
          if (suppressedExceptions == null) // Suppressed exceptions not recorded