Fix NullAway suppression in PulsarConfiguration

See gh-46587

module/spring-boot-pulsar/src/main/java/org/springframework/boot/pulsar/autoconfigure/PulsarConfiguration.java

@@ -53,6 +53,7 @@ import org.springframework.pulsar.function.PulsarFunction;
 import org.springframework.pulsar.function.PulsarFunctionAdministration;
 import org.springframework.pulsar.function.PulsarSink;
 import org.springframework.pulsar.function.PulsarSource;
+import org.springframework.util.Assert;
 
 /**
  * Common configuration used by both {@link PulsarAutoConfiguration} and
@@ -146,10 +147,11 @@ class PulsarConfiguration {
 		}
 	}
 
-	@SuppressWarnings("NullAway") // Resolved.orElseThrow() doesn't return nullable
 	private Schema<Object> getSchema(DefaultSchemaResolver schemaResolver, SchemaType schemaType, Class<?> messageType,
 			@Nullable Class<?> messageKeyType) {
-		return schemaResolver.resolveSchema(schemaType, messageType, messageKeyType).orElseThrow();
+		Schema<Object> schema = schemaResolver.resolveSchema(schemaType, messageType, messageKeyType).orElseThrow();
+		Assert.state(schema != null, "'schema' must not be null");
+		return schema;
 	}
 
 	@SuppressWarnings("unchecked")