When there are 2 custom fields with the same name, Xporter should export the one with a lower ID

When there are 2 custom fields with the same name, Xporter should export the one with a lower ID.

Currently, when we have several custom fields with the same name, Xporter is retrieving the first on Jira returns (unless we use the CF ID).
Jira doesn't always return these fields in the same order. We should export the CF with a lower ID.

This scenario is happening in the following automation tests:

• TestEX-51_Template18
• Bulk18Never_Template18
• Bulk20IssueTypes
• TestEX-51_Template22
• Bulk22Never_Template22

Test Case:
<suite-file path="docx_suites/testTemplate18.xml" />
<suite-file path="docx_suites/testTemplate20.xml" />
<suite-file path="docx_suites/testTemplate22.xml" />

Templates:
Xporter Test Template nº 18
Xporter Test Template nº 20
Xporter Test Template nº 22

Custom Field:
Elsa.