code: def validate(self):
      
      if self._validated_binaries:
        return
  
      with self._valid_executable('java') as java:
        if self._minimum_version:
          version = self._get_version(java)
          if version < self._minimum_version:
            raise self.Error('The java distribution at {} is too old; expecting at least {} and'
                             ' got {}'.format(java, self._minimum_version, version))
        if self._maximum_version:
          version = self._get_version(java)
          if version > self._maximum_version:
            raise self.Error('The java distribution at {} is too new; expecting no older than'
                             ' {} and got {}'.format(java, self._maximum_version, version))
  
      # We might be a JDK discovered by the embedded jre `java` executable.
      # If so reset the bin path to the true JDK home dir for full access to all binaries.
      self._bin_path = os.path.join(self.home, 'bin')
  
      try:
        self._validated_executable('javac')  # Calling purely for the check and cache side effects
        self._is_jdk = True
      except self.Error as e:
        if self._jdk:
          logger.debug('Failed to validate javac executable. Please check you have a JDK '
                        'installed. Original error: {}'.format(e))
          raise
docs: Validates this distribution against its configured constraints.
  
      Raises Distribution.Error if this distribution is not valid according to the configured
      constraints.