Document the change in behavior for SA1509

At the same time, the implementation of the new behavior was greatly
simplified.

Author: sharwell

StyleCop.Analyzers/StyleCop.Analyzers/LayoutRules/SA1509OpeningBracesMustNotBePrecededByBlankLine.cs

@@ -80,16 +80,9 @@ private static void HandleSyntaxTree(SyntaxTreeAnalysisContext context)
 
             foreach (var openBrace in openBraces)
             {
-                BlockSyntax blockSyntax = openBrace.Parent as BlockSyntax;
-                if (blockSyntax != null)
+                if (openBrace.GetPreviousToken().IsKind(SyntaxKind.CloseBraceToken))
                 {
-                    BlockSyntax parentBlock = blockSyntax.Parent as BlockSyntax;
-                    if (parentBlock != null && parentBlock.Statements[0] != blockSyntax)
-                    {
-                        // Do not disallow a blank line before an independent block, unless it is the first child of its
-                        // parent.
-                        continue;
-                    }
+                    continue;
                 }
 
                 AnalyzeOpenBrace(context, openBrace);

documentation/SA1509.md

@@ -21,23 +21,43 @@ An opening brace within a C# element, statement, or expression is preceded by a
 
 ## Rule description
 
-To improve the readability of the code, StyleCop requires blank lines in certain situations, and prohibits blank lines in other situations. This results in a consistent visual pattern across the code, which can improve recognition and readability of unfamiliar code.
+To improve the readability of the code, StyleCop requires blank lines in certain situations, and prohibits blank lines
+in other situations. This results in a consistent visual pattern across the code, which can improve recognition and
+readability of unfamiliar code.
 
-A violation of this rule occurs when an opening brace is preceded by a blank line. For example:
+In general, a violation of this rule occurs when an opening brace is preceded by a blank line. For example, the
+following above would generate two instances of this violation, since there are two places where opening braces are
+preceded by blank lines.
 
 ```csharp
 public bool Enabled
 
 {
-    get 
+    get
 
-    { 
-        return this.enabled; 
+    {
+        return this.enabled;
     }
 }
 ```
 
-The code above would generate two instances of this violation, since there are two places where opening braces are preceded by blank lines.
+An exception to this rule occurs when the opening brace is preceded by a closing brace. When this occurs, a blank line
+will be required by [SA1513](SA1513.md). The following example shows correct use of blank lines:
+
+```csharp
+public bool Enabled
+{
+    get
+    {
+        {
+        }
+
+        {
+            return this.enabled;
+        }
+    }
+}
+```
 
 ## How to fix violations
 

documentation/SA1513.md

@@ -21,20 +21,24 @@ A closing brace within a C# element, statement, or expression is not followed by
 
 ## Rule description
 
-To improve the readability of the code, StyleCop requires blank lines in certain situations, and prohibits blank lines in other situations. This results in a consistent visual pattern across the code, which can improve recognition and readability of unfamiliar code.
+To improve the readability of the code, StyleCop requires blank lines in certain situations, and prohibits blank lines
+in other situations. This results in a consistent visual pattern across the code, which can improve recognition and
+readability of unfamiliar code.
 
-A violation of this rule occurs when a closing brace is not followed by a blank line. For example:
+A violation of this rule occurs when a closing brace is not followed by a blank line. For example, the following code
+would generate one instance of this violation, since there is one place where a closing brace is not followed by a blank
+line.
 
 ```csharp
 public bool Enabled
 {
-    get 
-    { 
-        return this.enabled; 
+    get
+    {
+        return this.enabled;
     }}
 ```
 
-The code above would generate one instance of this violation, since there is one place where a closing brace is not followed by a blank line.
+
 
 ## How to fix violations