Create rule S7158: String.isEmpty() should be used to test for emptiness (#4493)

rules/S7158/java/metadata.json

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+{
+  "title": "\"String.isEmpty()\" should be used to test for emptiness",
+  "type": "CODE_SMELL",
+  "status": "ready",
+  "remediation": {
+    "func": "Constant\/Issue",
+    "constantCost": "2min"
+  },
+  "tags": [],
+  "defaultSeverity": "Minor",
+  "ruleSpecification": "RSPEC-7158",
+  "sqKey": "S7158",
+  "scope": "All",
+  "defaultQualityProfiles": [
+    "Sonar way"
+  ],
+  "quickfix": "targeted",
+  "code": {
+    "impacts": {
+      "MAINTAINABILITY": "LOW"
+    },
+    "attribute": "CLEAR"
+  }
+}

rules/S7158/java/rule.adoc

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+== Why is this an issue?
+
+Calling `String.isEmpty()` clearly communicates the code's intention, which is to test if the string is empty. Using `String.length() == 0` is less direct and makes the code less readable.
+
+== How to fix it
+
+=== Code examples
+
+==== Noncompliant code example
+[source,java,diff-id=1,diff-type=noncompliant]
+----
+if ("string".length() == 0) { /* … */ } // Noncompliant
+
+if ("string".length() > 0) { /* … */ } // Noncompliant
+----
+
+==== Compliant solution
+[source,java,diff-id=1,diff-type=compliant]
+----
+if ("string".isEmpty()){ /* … */ }
+
+if (!"string".isEmpty()){ /* … */ }
+----
+
+== Resources
+=== Documentation
+
+* Java Documentation - https://docs.oracle.com/javase/7/docs/api/java/lang/String.html#isEmpty()[java.lang.String.isEmpty() method]

rules/S7158/metadata.json

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+{
+}