Refactor JWTCondition to use execution calls instead of inheriting from them

The rationale for this is to keep the ExecutionCall abstraction to encapsulate the JWT verification logic, but without inheriting from ExecutionCallAccessControlConditions, which require ReturnValueTests, something that JWTConditions don't need.

nucypher/policy/conditions/jwt.py

@@ -6,17 +6,13 @@ from cryptography.hazmat.primitives.asymmetric import ec, rsa
 from cryptography.hazmat.primitives.serialization import load_pem_public_key
 from marshmallow import ValidationError, fields, post_load, validate, validates
 
-from nucypher.policy.conditions.base import ExecutionCall
+from nucypher.policy.conditions.base import AccessControlCondition, ExecutionCall
 from nucypher.policy.conditions.context import (
     is_context_variable,
     resolve_any_context_variables,
 )
-from nucypher.policy.conditions.exceptions import JWTException
-from nucypher.policy.conditions.lingo import (
-    ConditionType,
-    ExecutionCallAccessControlCondition,
-    ReturnValueTest,
-)
+from nucypher.policy.conditions.exceptions import InvalidCondition, JWTException
+from nucypher.policy.conditions.lingo import ConditionType
 from nucypher.utilities.logging import Logger
 
 
@@ -105,19 +101,16 @@ class JWTVerificationCall(ExecutionCall):
         return payload
 
 
-class JWTCondition(ExecutionCallAccessControlCondition):
+class JWTCondition(AccessControlCondition):
     """
     A JWT condition can be satisfied by presenting a valid JWT token, which not only is
     required to be cryptographically verifiable, but also must fulfill certain additional
     restrictions defined in the condition.
     """
 
-    EXECUTION_CALL_TYPE = JWTVerificationCall
     CONDITION_TYPE = ConditionType.JWT.value
 
-    class Schema(
-        ExecutionCallAccessControlCondition.Schema, JWTVerificationCall.Schema
-    ):
+    class Schema(AccessControlCondition.Schema, JWTVerificationCall.Schema):
         condition_type = fields.Str(
             validate=validate.Equal(ConditionType.JWT.value), required=True
         )
@@ -134,16 +127,16 @@ class JWTCondition(ExecutionCallAccessControlCondition):
         name: Optional[str] = None,
         expected_issuer: Optional[str] = None,
     ):
-        super().__init__(
-            jwt_token=jwt_token,
-            public_key=public_key,
-            expected_issuer=expected_issuer,
-            condition_type=condition_type,
-            name=name,
-            return_value_test=ReturnValueTest(
-                comparator="==", value=True
-            ),  # TODO: Workaround for now
-        )
+        try:
+            self.execution_call = JWTVerificationCall(
+                jwt_token=jwt_token,
+                public_key=public_key,
+                expected_issuer=expected_issuer,
+            )
+        except ExecutionCall.InvalidExecutionCall as e:
+            raise InvalidCondition(str(e)) from e
+
+        super().__init__(condition_type=condition_type, name=name)
 
     @property
     def jwt_token(self):