| AbstractDiffEvaluator | Provides a default diff evaluator implementation with utility methods
 for emitting events of different severities. | 
| AddedEntityBinding | A meta-validator that emits a NOTE when an operation resource is added
 to a service or resource entity. | 
| AddedMetadata | Creates a NOTE event when metadata is added. | 
| AddedOperationError | Emits a warning when an error is added to an operation. | 
| AddedOperationInputOutput | Meta-validator that emits a NOTE when a backward compatible operation
 input or output is added (AddedOperationInput and AddedOperationOutput),
 and an ERROR when a breaking operation input is added using the same
 event IDs. | 
| AddedShape | Creates a NOTE event when a shape is added. | 
| AddedTraitDefinition | Creates a NOTE event when a trait definition is added. | 
| ChangedEnumTrait | Emits a NOTE when a new enum value is added, emits an ERROR when an
 enum value is removed, and emits an ERROR when an enum name changes. | 
| ChangedLengthTrait | Detects when the Length trait is made more restrictive by either
 raising the min or lowering the max. | 
| ChangedMemberOrder | Creates a DANGER event when a structure or union member is added
 anywhere other than the end of the previous definition or the
 member order is changed. | 
| ChangedMemberTarget | Checks for changes in the shapes targeted by a member. | 
| ChangedMetadata | Creates a WARNING event when metadata is changed. | 
| ChangedOperationInput | Emits an ERROR when the input shape of an operation is changed to
 another shape. | 
| ChangedOperationOutput | Emits an ERROR when the output shape of an operation is changed to
 another shape. | 
| ChangedRangeTrait | Detects when the Range trait is made more restrictive by either
 raising the min or lowering the max. | 
| ChangedResourceIdentifiers | Creates an ERROR event when the identifiers of a resource changes. | 
| ChangedShapeType | Creates an ERROR event when the type of a shape changes. | 
| ModifiedTrait | Finds breaking changes related to when a trait is added, removed, or
 updated. | 
| RemovedAuthenticationScheme | TODO: Implement evaluator to find removed authentication schemes. | 
| RemovedEntityBinding | A meta-validator that checks for the removal of an operation or
 resource binding from a service or resource. | 
| RemovedMetadata | Creates a DANGER event when metadata is removed. | 
| RemovedOperationError | Emits a warning when an error is removed from an operation. | 
| RemovedOperationInput | Emits an ERROR when the input shape is removed from an operation. | 
| RemovedOperationOutput | Emits an ERROR when the output shape is removed from an operation. | 
| RemovedShape | Creates an ERROR event when a non-private shape is removed. | 
| RemovedTraitDefinition | Creates an ERROR event when a trait definition is removed. |