SONARJAVA-5502 Jot down first notes

Author: dorian-burihabwa-sonarsource

rules/S7480/java/metadata.json

@@ -1,10 +1,10 @@
 {
-  "title": "FIXME",
+  "title": "The result of \"Downstream.push\" should not be ignored",
   "type": "CODE_SMELL",
   "status": "ready",
   "remediation": {
     "func": "Constant\/Issue",
-    "constantCost": "5min"
+    "constantCost": "15min"
   },
   "tags": [
   ],
@@ -13,13 +13,12 @@
   "sqKey": "S7480",
   "scope": "All",
   "defaultQualityProfiles": ["Sonar way"],
-  "quickfix": "unknown",
+  "quickfix": "infeasible",
   "code": {
     "impacts": {
-      "MAINTAINABILITY": "HIGH",
-      "RELIABILITY": "MEDIUM",
-      "SECURITY": "LOW"
+      "MAINTAINABILITY": "LOW",
+      "RELIABILITY": "MEDIUM"
     },
-    "attribute": "CONVENTIONAL"
+    "attribute": "LOGICAL"
   }
 }

rules/S7480/java/rule.adoc

@@ -1,7 +1,7 @@
-FIXME: add a description
+The integrator function can pass data downstream using the push method
+In return, the stream should return a result indicating whether it accepted the latest value.
 
-// If you want to factorize the description uncomment the following line and create the file.
-//include::../description.adoc[]
+Ignoring the value returned by `Downstream.push` might lead to inconsistent behavior of the integrator.
 
 == Why is this an issue?
 
@@ -18,14 +18,39 @@ FIXME: remove the unused optional headers (that are commented out)
 
 [source,java,diff-id=1,diff-type=noncompliant]
 ----
-FIXME
+Gatherer.ofSequential(
+  () -> new AtomicInteger(100),
+  (state, element, downstream) -> {
+      int newState = state.addAndGet(element);
+      downstream.push(newState); // Noncompliant: ignoring return value
+      return true;
+  });
 ----
 
 ==== Compliant solution
 
 [source,java,diff-id=1,diff-type=compliant]
 ----
-FIXME
+Gatherer.ofSequential(
+  () -> new AtomicInteger(100),
+  (state, element, downstream) -> {
+      int newState = state.addAndGet(element);
+      return downstream.push(newState); // Compliant
+  });
+----
+
+[source,java,diff-id=1,diff-type=compliant]
+----
+Gatherer.ofSequential(
+  () -> new AtomicInteger(100),
+  (state, element, downstream) -> {
+      int newState = state.addAndGet(element);
+      if (downstream.push(newState)) {
+        // Do something to handle this specific case
+        return false;
+      }
+      return true;
+  });
 ----
 
 //=== How does this work?