src/java.base/share/classes/sun/nio/cs/ISO_8859_1.java

*** 130,139 ****
--- 130,143 ----
              int dp = 0;
              while (dp < len)
                  dst[dp++] = (char)(src[sp++] & 0xff);
              return dp;
          }
+ 
+         public boolean isASCIICompatible() {
+             return true;
+         }
      }
  
      private static class Encoder extends CharsetEncoder
                                   implements ArrayEncoder {
          private Encoder(Charset cs) {
*** 295,301 ****
--- 299,309 ----
                      slen = Math.min((sl - sp), (dst.length - dp));
                  }
              }
              return dp;
          }
+ 
+         public boolean isASCIICompatible() {
+             return true;
+         }
      }
  }