code: public String firstCalledName() {
          if( addr instanceof NbtAddress ) {
              return ((NbtAddress)addr).firstCalledName();
          } else {
              calledName = ((InetAddress)addr).getHostName();
              if( isDotQuadIP( calledName )) {
                  calledName = NbtAddress.SMBSERVER_NAME;
              } else {
                  int i = calledName.indexOf( '.' );
                  if( i > 1 && i < 15 ) {
                      calledName = calledName.substring( 0, i ).toUpperCase();
                  } else if( calledName.length() > 15 ) {
                      calledName = NbtAddress.SMBSERVER_NAME;
                  } else {
                      calledName = calledName.toUpperCase();
                  }
              }
          }
  
          return calledName;
      }
docs: Guess first called name to try for session establishment. This
  method is used exclusively by the <tt>jcifs.smb1.smb1</tt> package.