9aca5626a7
JIRA: https://jira.spring.io/browse/INT-3766 Previously the `GatewayProxyFactoryBean` detected the presence of `Environment` before looking for `Promise` return types. This caused initialization failures if `reactor-core` was on the classpath, but not `reactor-stream`. Change `reactorPresent` to look for the `Promise` class intead of `Environment`.