EurekaHealthCheckHandler: Added protected getter to obtain CompositeHealthIndicator (#2583)

* Adding protected getter to obtain CompositeHealthIndicator. This allows subclasses to obtain this indicator's health details map which is useful for error reporting.

spring-cloud-netflix-eureka-client/src/main/java/org/springframework/cloud/netflix/eureka/EurekaHealthCheckHandler.java

@@ -100,7 +100,7 @@ public class EurekaHealthCheckHandler implements HealthCheckHandler, Application
 	}
 
 	protected InstanceStatus getHealthStatus() {
-		final Status status = healthIndicator.health().getStatus();
+		final Status status = getHealthIndicator().health().getStatus();
 		return mapToInstanceStatus(status);
 	}
 
@@ -110,4 +110,8 @@ public class EurekaHealthCheckHandler implements HealthCheckHandler, Application
 		}
 		return STATUS_MAPPING.get(status);
 	}
+
+	protected CompositeHealthIndicator getHealthIndicator() {
+		return healthIndicator;
+	}
 }