Spring-rest is broken in 1.17.0 release

[t92549]

This problem has been holding back a gaffer-docker 1.17.0 release.

The error is only present when run using the java command detailed in the README:

Gaffer/rest-api/spring-rest/README.md

Lines 42 to 50 in b22d7a7

	With java
	```
	java \
	-Dgaffer.schemas=/path/to/schemas \
	-Dgaffer.storeProperties=/path/to/store.properties \
	-Dgaffer.graph.config=/path/to/graphConfig.json \
	-Dloader.path=/path/to/external/libs \
	-jar target/spring-rest-1.13.1-SNAPSHOT.jar
	```

But does not happen when running the maven profile with: mvn spring-boot:run -pl :spring-rest -Pdemo.

This error is present in the 1.17.0 jars on maven central, but not the previous versions on maven central. Despite that, any local build of spring-rest 1.15.0 - 1.16.1 all still have this problem present, hinting at a problem with dependencies and caching before submission to maven central. The reason this then came to light in 1.17.0 is because the source code changed.

The actual problem is that when a connection is made to the spring rest api, the following error occurs:

[localhost].[/rest].[dispatcherServlet] ERROR  - Servlet.service() for servlet [dispatcherServlet] in context with path [/rest] threw exception [Request processing failed; nested exception is java.lang.IllegalStateException: Already connected] with root cause
java.lang.IllegalStateException: Already connected
        at java.net.URLConnection.setUseCaches(URLConnection.java:989)
        at org.springframework.util.ResourceUtils.useCachesIfNecessary(ResourceUtils.java:388)
        at org.springframework.core.io.AbstractFileResolvingResource.customizeConnection(AbstractFileResolvingResource.java:190)
        at org.springframework.core.io.AbstractFileResolvingResource.contentLength(AbstractFileResolvingResource.java:159)
        at org.springframework.web.servlet.resource.ResourceHttpRequestHandler.setHeaders(ResourceHttpRequestHandler.java:433)
        at org.springframework.web.servlet.resource.ResourceHttpRequestHandler.handleRequest(ResourceHttpRequestHandler.java:270)
        at org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter.handle(HttpRequestHandlerAdapter.java:51)
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959)
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893)
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:969)
        at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:860)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:687)
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:845)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
        at uk.gov.gchq.gaffer.rest.filter.GafferHeaderFilter.doFilterInternal(GafferHeaderFilter.java:40)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
        at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
        at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:87)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
        at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
        at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:121)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:521)
        at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1096)
        at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:674)
        at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
        at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.lang.Thread.run(Thread.java:748)

[t92549]

Closed due to #2469