Generate MARC bib record - Identifiers part IV - appending subfields

Purpose
FOLIO inventory storage instance contains fields that are represented by keys and those will need to be replaced by their values when generating MARC bib record on the fly. In many cases, which field in MARC record will be populated depends on the value of the key. For identifiers, depending on its type the different MARC Bib record field will be populated. Each inventory instance has a list of identifiers associated with it and it is an array of identifier value and identifier type id.

Requirements/Scope:

1. ASIN - 024$a (first indicator set to 8, second indicator is blank), the identifier type (value) will populate $q
   If the record already contains 024 $a, the field and subfield are repeated
2. BNB - 024$a (first indicator set to 8, second indicator is blank),the identifier type (value) will populate $q
   If the record already contains 024 $a, the field and subfield are repeated
3. Local identifiers- 024$a (first indicator set to 8, second indicator is blank), the identifier type (value) will populate $q
4. StEdNL - 024$a (first indicator set to 8, second indicator is blank), the identifier type (value) will populate $q
   If the record already contains 024 $a, the field and subfield are repeated
5. UKMac - 024$a (first indicator set to 8, second indicator is blank), the identifier type (value) will populate $q
   If the record already contains 024 $a, the field and subfield are repeated

Additional information:

• List of identifiers API: /identifier-types
• Default mapping rules: https://github.com/folio-org/mod-data-export/blob/master/src/main/resources/rules/rulesDefault.json
  For the details of the mapping refer to Recommended MARC mapping spreadsheet: https://docs.google.com/spreadsheets/d/11lGBiPoetHuC3u-onVVLN4Mj5KtVHqJaQe4RqCxgGzo/edit#gid=1166940623 Instance to MARC t2021 ab.
• MARC documentation for related fields: https://www.loc.gov/marc/bibliographic/bd01x09x.html

Approach:

Acceptance criteria:

1. The generated record is short-lived and generated each time it is requested
2. The specified identifiers are being correctly mapped according to the mapping document:
3. The record is saved in .mrc file and contains correctly populated data
4. Unit tests are written
5. API tests are written