Contention fix introduced a HTTP metadata provider editing & saving issue

Steps to reproduce:

1. Create an http-type provider, save
2. Add an entity attributes filter
3. Edit the provider, make a change and save

Expected result: The provider should save as normal
Actual result: A long toast 400 is displayed containing things like:

400 - Multiple representations of the same entity edu.internet2.tier.shibboleth.admin.ui.domain.filters.EntityAttributesFilter#124 are being merged. Detached: [EntityAttributesFilter(attributes=[], attributeRelease=[], entityAttributesFilterTarget=EntityAttributesFilterTarget

{entityAttributesFilterTargetType=ENTITY, value=[1]}, relyingPartyOverrides={})]; Detached: [EntityAttributesFilter(attributes=[], attributeRelease=[], entityAttributesFilterTarget=EntityAttributesFilterTarget{entityAttributesFilterTargetType=ENTITY, value=[1]}

, relyingPartyOverrides={})]; nested exception is java.lang.IllegalStateException: Multiple representations of the same entity edu.internet2.tier.shibboleth.admin.ui.domain.filters.EntityAttributesFilter#124 are being merged. Detached: [EntityAttributesFilter(attributes=[], attributeRelease=[], entityAttributesFilterTarget=EntityAttributesFilterTarget

{entityAttributesFilterTargetType=ENTITY, value=[1]}, relyingPartyOverrides={})]; Detached: [EntityAttributesFilter(attributes=[], attributeRelease=[], entityAttributesFilterTarget=EntityAttributesFilterTarget{entityAttributesFilterTargetType=ENTITY, value=[1]}

, relyingPartyOverrides={})]