INT-4448, INT-4449: Fix Gateway for no-arg method (#2420)
* INT-4448, INT-4449: Fix Gateway for no-arg method
JIRA: https://jira.spring.io/browse/INT-4448
JIRA: https://jira.spring.io/browse/INT-4449
When we are not interested in the `payload` to send, we use a gateway
method without any args, but in this case for send operation (or
send-and-receive) we should specify a default `payloadExpression`
The `MessagingGatewayRegistrar` fails with `NPE` if we don't have a
any global headers and have `defaultPayloadExpression`
Also in this case the `GatewayProxyFactoryBean` fails to send
and fallbacks to receive with the meaning "no args, not payloadExpression"
* Fix `MessagingGatewayRegistrar` to check `hasDefaultHeaders` before
processing them
* Fix `GatewayProxyFactoryBean` to consult `this.globalMethodMetadata`
if there is no `payloadExpression` for the method specific metadata
**Cherry-pick to 5.0.x and 4.3.x**
* Remove `oracle-java8-installer` since it looks like the resource
is not available anymore:
```
Location: http://download.oracle.com/otn-pub/java/jdk/8u161-b12/2f38c3b165be4555a1fa6e98c45e0808/jdk-8u161-linux-x64.tar.gz?AuthParam=1523990114_ee8c82cbe67bc87d192cb79d3b902d2f [following]
--2018-04-17 18:33:14-- http://download.oracle.com/otn-pub/java/jdk/8u161-b12/2f38c3b165be4555a1fa6e98c45e0808/jdk-8u161-linux-x64.tar.gz?AuthParam=1523990114_ee8c82cbe67bc87d192cb79d3b902d2f
Connecting to download.oracle.com (download.oracle.com)|23.53.120.105|:80... connected.
HTTP request sent, awaiting response... 404 Not Found
2018-04-17 18:35:15 ERROR 404: Not Found.
```
dc095322a2