def generate_properties_text(secret_key_hexstring, additional_properties=None):
    """
    Returns 'kettle.properties' file contents with AES encryption config

    Keyword Parameters:
    secret_key_hexstring  - String, representing a symmetric AES
      encryption key encoded as hexadecimal text
    additional_properties  -- String, representing additional Java
      properties to be appended to end of config (Optional)

    >>> from pprint import pprint
    >>> fake_key = "01001100DEADBEEF"
    >>> out = generate_properties_text(fake_key)
    >>> pprint(out)
    ('# This file was generated by FRAM Data Warehouse\\n'
     '# (based on template from Pentaho Data Integration version 6.1.0.1-196)\\n'
     '#\\n'
     '# Here are a few examples of variables to set:\\n'
     '#\\n'
     '# PRODUCTION_SERVER = hercules\\n'
     '# TEST_SERVER = zeus\\n'
     '# DEVELOPMENT_SERVER = thor\\n'
     '#\\n'
     '# Note: lines like these with a # in front of it are comments\\n'
     '#\\n'
     'KETTLE_PASSWORD_ENCODER_PLUGIN = Aes256_Encrypted\\n'
     'KETTLE_PASSWORD_ENCODER_KEY = 01001100DEADBEEF')
    >>> pprint(generate_properties_text(fake_key, 'myProp=extra'))
    ('# This file was generated by FRAM Data Warehouse\\n'
     '# (based on template from Pentaho Data Integration version 6.1.0.1-196)\\n'
     '#\\n'
     '# Here are a few examples of variables to set:\\n'
     '#\\n'
     '# PRODUCTION_SERVER = hercules\\n'
     '# TEST_SERVER = zeus\\n'
     '# DEVELOPMENT_SERVER = thor\\n'
     '#\\n'
     '# Note: lines like these with a # in front of it are comments\\n'
     '#\\n'
     'KETTLE_PASSWORD_ENCODER_PLUGIN = Aes256_Encrypted\\n'
     'KETTLE_PASSWORD_ENCODER_KEY = 01001100DEADBEEF\\n'
     'myProp=extra')
    """
    template = """# This file was generated by FRAM Data Warehouse
# (based on template from Pentaho Data Integration version 6.1.0.1-196)
#
# Here are a few examples of variables to set:
#
# PRODUCTION_SERVER = hercules
# TEST_SERVER = zeus
# DEVELOPMENT_SERVER = thor
#
# Note: lines like these with a # in front of it are comments
#
KETTLE_PASSWORD_ENCODER_PLUGIN = Aes256_Encrypted
KETTLE_PASSWORD_ENCODER_KEY = {}"""
    properties = template.format(secret_key_hexstring)
    if additional_properties is not None:
        properties += '\n' + additional_properties
    return properties