The solution was from the ticket
https://github.com/schemaspy/schemaspy/issues/804
The file \BOOT-INF\classes\org\schemaspy\types\mssql08.properties was updated accordingly.
old:
selectRoutinesSql=SELECT i_s.routine_name, i_s.routine_type, i_s.data_type AS dtd_identifier, i_s.routine_body, i_s.routine_definition, i_s.is_deterministic, i_s.sql_data_access, \
NULL AS security_type, NULL AS sql_mode, CAST(s.value AS NVARCHAR(MAX)) AS routine_comment \
FROM information_schema.routines i_s LEFT JOIN sys.extended_properties s ON s.major_id = OBJECT_ID(i_s.routine_catalog + '.' + i_s.routine_schema + '.' + i_s.routine_name) AND s.class = 1 AND s.name = 'MS_Description' AND s.minor_id = 0 \
WHERE routine_schema = :schema
new:
selectRoutinesSql=SELECT i_s.routine_name, i_s.routine_type, i_s.data_type AS dtd_identifier, i_s.routine_body, (SELECT modules.definition FROM sys.sql_modules modules WHERE object_id=OBJECT_ID(routine_schema+'.'+i_s.routine_name)) AS routine_definition, i_s.is_deterministic, i_s.sql_data_access, \
NULL AS security_type, NULL AS sql_mode, CAST(s.value AS NVARCHAR(MAX)) AS routine_comment \
FROM information_schema.routines i_s LEFT JOIN sys.extended_properties s ON s.major_id = OBJECT_ID(i_s.routine_catalog + '.' + i_s.routine_schema + '.' + i_s.routine_name) AND s.class = 1 AND s.name = 'MS_Description' AND s.minor_id = 0 \
WHERE routine_schema = :schema
For any update of the SchemaSpy version this change must be considered and applied to the new jar file.