[CLEANUP] And some more annotations for non-empty strings

src/CSSList/AtRuleBlockList.php

@@ -46,6 +46,9 @@ public function atRuleArgs(): string
         return $this->arguments;
     }
 
+    /**
+     * @return non-empty-string
+     */
     public function render(OutputFormat $outputFormat): string
     {
         $formatter = $outputFormat->getFormatter();

src/CSSList/KeyFrame.php

@@ -51,6 +51,9 @@ public function getAnimationName(): string
         return $this->animationName;
     }
 
+    /**
+     * @return non-empty-string
+     */
     public function render(OutputFormat $outputFormat): string
     {
         $formatter = $outputFormat->getFormatter();

src/Comment/Comment.php

@@ -50,6 +50,9 @@ public function setComment(string $commentText): void
         $this->commentText = $commentText;
     }
 
+    /**
+     * @return non-empty-string
+     */
     public function render(OutputFormat $outputFormat): string
     {
         return '/*' . $this->commentText . '*/';

src/OutputFormat.php

@@ -9,7 +9,7 @@ final class OutputFormat
     /**
      * Value format: `"` means double-quote, `'` means single-quote
      *
-     * @var string
+     * @var non-empty-string
      */
     private $stringQuotingType = '"';
 
@@ -181,6 +181,8 @@ final class OutputFormat
     private $indentationLevel = 0;
 
     /**
+     * @return non-empty-string
+     *
      * @internal
      */
     public function getStringQuotingType(): string
@@ -189,6 +191,8 @@ public function getStringQuotingType(): string
     }
 
     /**
+     * @param non-empty-string $quotingType
+     *
      * @return $this fluent interface
      */
     public function setStringQuotingType(string $quotingType): self

src/Property/CSSNamespace.php

@@ -55,6 +55,9 @@ public function getLineNo(): int
         return $this->lineNumber;
     }
 
+    /**
+     * @return non-empty-string
+     */
     public function render(OutputFormat $outputFormat): string
     {
         return '@namespace ' . ($this->prefix === null ? '' : $this->prefix . ' ')

src/Property/Charset.php

@@ -68,6 +68,9 @@ public function getCharset(): string
         return $this->charset->getString();
     }
 
+    /**
+     * @return non-empty-string
+     */
     public function render(OutputFormat $outputFormat): string
     {
         return "{$outputFormat->getFormatter()->comments($this)}@charset {$this->charset->render($outputFormat)};";

src/Property/Import.php

@@ -65,6 +65,9 @@ public function getLocation(): URL
         return $this->location;
     }
 
+    /**
+     * @return non-empty-string
+     */
     public function render(OutputFormat $outputFormat): string
     {
         return $outputFormat->getFormatter()->comments($this) . '@import ' . $this->location->render($outputFormat)

src/RuleSet/AtRuleSet.php

@@ -49,6 +49,9 @@ public function atRuleArgs(): string
         return $this->arguments;
     }
 
+    /**
+     * @return non-empty-string
+     */
     public function render(OutputFormat $outputFormat): string
     {
         $formatter = $outputFormat->getFormatter();

src/RuleSet/DeclarationBlock.php

@@ -138,6 +138,8 @@ public function getSelectors(): array
     }
 
     /**
+     * @return non-empty-string
+     *
      * @throws OutputException
      */
     public function render(OutputFormat $outputFormat): string

src/Value/CSSFunction.php

@@ -105,6 +105,9 @@ public function getArguments(): array
         return $this->components;
     }
 
+    /**
+     * @return non-empty-string
+     */
     public function render(OutputFormat $outputFormat): string
     {
         $arguments = parent::render($outputFormat);

src/Value/CSSString.php

@@ -83,6 +83,9 @@ public function getString(): string
         return $this->string;
     }
 
+    /**
+     * @return non-empty-string
+     */
     public function render(OutputFormat $outputFormat): string
     {
         $string = \addslashes($this->string);

src/Value/Color.php

@@ -224,6 +224,9 @@ public function getColorDescription(): string
         return $this->getName();
     }
 
+    /**
+     * @return non-empty-string
+     */
     public function render(OutputFormat $outputFormat): string
     {
         if ($this->shouldRenderAsHex($outputFormat)) {

src/Value/LineName.php

@@ -49,6 +49,9 @@ public static function parse(ParserState $parserState): LineName
         return new LineName($names, $parserState->currentLine());
     }
 
+    /**
+     * @return non-empty-string
+     */
     public function render(OutputFormat $outputFormat): string
     {
         return '[' . parent::render(OutputFormat::createCompact()) . ']';

src/Value/Size.php

@@ -195,6 +195,9 @@ public function isRelative(): bool
         return false;
     }
 
+    /**
+     * @return non-empty-string
+     */
     public function render(OutputFormat $outputFormat): string
     {
         $locale = \localeconv();

src/Value/URL.php

@@ -73,6 +73,9 @@ public function getURL(): CSSString
         return $this->url;
     }
 
+    /**
+     * @return non-empty-string
+     */
     public function render(OutputFormat $outputFormat): string
     {
         return "url({$this->url->render($outputFormat)})";