code: private static boolean nonCharacterCodePoint(final int codepoint) {
          return 0xFDD0 <= codepoint && codepoint <= 0xFDEF
                  || 0xFFFE <= codepoint && codepoint <= 0xFFFF
                  || 0x1FFFE <= codepoint && codepoint <= 0x1FFFF
                  || 0x2FFFE <= codepoint && codepoint <= 0x2FFFF
                  || 0x3FFFE <= codepoint && codepoint <= 0x3FFFF
                  || 0x4FFFE <= codepoint && codepoint <= 0x4FFFF
                  || 0x5FFFE <= codepoint && codepoint <= 0x5FFFF
                  || 0x6FFFE <= codepoint && codepoint <= 0x6FFFF
                  || 0x7FFFE <= codepoint && codepoint <= 0x7FFFF
                  || 0x8FFFE <= codepoint && codepoint <= 0x8FFFF
                  || 0x9FFFE <= codepoint && codepoint <= 0x9FFFF
                  || 0xAFFFE <= codepoint && codepoint <= 0xAFFFF
                  || 0xBFFFE <= codepoint && codepoint <= 0xBFFFF
                  || 0xCFFFE <= codepoint && codepoint <= 0xCFFFF
                  || 0xDFFFE <= codepoint && codepoint <= 0xDFFFF
                  || 0xEFFFE <= codepoint && codepoint <= 0xEFFFF
                  || 0xFFFFE <= codepoint && codepoint <= 0xFFFFF
                  || 0x10FFFE <= codepoint && codepoint <= 0x10FFFF;
      }
docs: Return true if the given {@code codepoint} is a non-character code point as defined by
  <a href="https://tools.ietf.org/html/rfc3454#appendix-C.4">RFC 3454, Appendix C.4</a>.