private static Class<?> extractType(Class<?> paramClass, Field field) {
		Class<?> type = field.getType();
		if (field.getGenericType() instanceof TypeVariable<?>) {
			Type fieldType = GenericTypeResolver.resolveType(field.getGenericType(), paramClass);

			if (fieldType instanceof Class<?>)
				type = (Class<?>) fieldType;
			else    // This is the case for not reifiable types
				type = null;
		}

		return type;
	}
Extract the type

@param paramClass the param class
@param field      the field
@return The revoled type or null if it was not a reifiable type
springdoc-openapi-starter-common/src/main/java/org/springdoc/core/extractor/MethodParameterPojoExtractor.java