Adds pattern example generation

Author: spacether

samples/client/petstore/java/docs/components/schemas/Apple.md

@@ -45,11 +45,11 @@ Apple.AppleMap validatedPayload =
     MapMaker.makeMap(
         new AbstractMap.SimpleEntry<>(
             "cultivar",
-            "a"
+            "\ziEEpmVvrKlTttzGFqCEG"
         ),
         new AbstractMap.SimpleEntry<>(
             "origin",
-            "a"
+            "\ziEEpmVvrKlTttzGFqCEG"
         )
     ),
     configuration
@@ -114,7 +114,7 @@ static final SchemaConfiguration configuration = new SchemaConfiguration(JsonSch
 
 // String validation
 String validatedPayload = Apple.Origin.validate(
-    "a",
+    "\ziEEpmVvrKlTttzGFqCEG",
     configuration
 );
 ```
@@ -152,7 +152,7 @@ static final SchemaConfiguration configuration = new SchemaConfiguration(JsonSch
 
 // String validation
 String validatedPayload = Apple.Cultivar.validate(
-    "a",
+    "\ziEEpmVvrKlTttzGFqCEG",
     configuration
 );
 ```

samples/client/petstore/java/docs/components/schemas/ComposedOneOfDifferentTypes.md

@@ -66,7 +66,7 @@ static final SchemaConfiguration configuration = new SchemaConfiguration(JsonSch
 
 // String validation
 String validatedPayload = ComposedOneOfDifferentTypes.Schema6.validate(
-    "1970-01-01T00:00:00.00Z",
+    "2020jUR,rZ#UM/?R,Fp^l6$ARj",
     configuration
 );
 ```

samples/client/petstore/java/docs/components/schemas/DateTimeWithValidations.md

@@ -32,7 +32,7 @@ static final SchemaConfiguration configuration = new SchemaConfiguration(JsonSch
 
 // String validation
 String validatedPayload = DateTimeWithValidations.DateTimeWithValidations1.validate(
-    "1970-01-01T00:00:00.00Z",
+    "2020jUR,rZ#UM/?R,Fp^l6$ARj",
     configuration
 );
 ```

samples/client/petstore/java/docs/components/schemas/DateWithValidations.md

@@ -32,7 +32,7 @@ static final SchemaConfiguration configuration = new SchemaConfiguration(JsonSch
 
 // String validation
 String validatedPayload = DateWithValidations.DateWithValidations1.validate(
-    "2020-12-13",
+    "2020jUR,rZ#UM/?R,Fp^l6$ARj",
     configuration
 );
 ```

samples/client/petstore/java/docs/components/schemas/FormatTest.md

@@ -114,7 +114,7 @@ FormatTest.FormatTestMap validatedPayload =
         ),
         new AbstractMap.SimpleEntry<>(
             "string",
-            "a"
+            "A"
         ),
         new AbstractMap.SimpleEntry<>(
             "binary",
@@ -134,11 +134,11 @@ FormatTest.FormatTestMap validatedPayload =
         ),
         new AbstractMap.SimpleEntry<>(
             "pattern_with_digits",
-            "a"
+            "\dddddddddd"
         ),
         new AbstractMap.SimpleEntry<>(
             "pattern_with_digits_and_delimiter",
-            "a"
+            "IMage_\dd"
         ),
         new AbstractMap.SimpleEntry<>(
             "noneProp",
@@ -251,7 +251,7 @@ static final SchemaConfiguration configuration = new SchemaConfiguration(JsonSch
 
 // String validation
 String validatedPayload = FormatTest.PatternWithDigitsAndDelimiter.validate(
-    "a",
+    "IMage_\dd",
     configuration
 );
 ```
@@ -292,7 +292,7 @@ static final SchemaConfiguration configuration = new SchemaConfiguration(JsonSch
 
 // String validation
 String validatedPayload = FormatTest.PatternWithDigits.validate(
-    "a",
+    "\dddddddddd",
     configuration
 );
 ```
@@ -420,7 +420,7 @@ static final SchemaConfiguration configuration = new SchemaConfiguration(JsonSch
 
 // String validation
 String validatedPayload = FormatTest.StringSchema.validate(
-    "a",
+    "A",
     configuration
 );
 ```

samples/client/petstore/java/docs/paths/fake/post/requestbody/content/applicationxwwwformurlencoded/Schema.md

@@ -63,7 +63,7 @@ Schema.SchemaMap validatedPayload =
         ),
         new AbstractMap.SimpleEntry<>(
             "pattern_without_delimiter",
-            "a"
+            "AUR,rZ#UM/?R,Fp^l6$ARjbhJk C>"
         ),
         new AbstractMap.SimpleEntry<>(
             "integer",
@@ -83,7 +83,7 @@ Schema.SchemaMap validatedPayload =
         ),
         new AbstractMap.SimpleEntry<>(
             "string",
-            "a"
+            "A"
         ),
         new AbstractMap.SimpleEntry<>(
             "binary",
@@ -315,7 +315,7 @@ static final SchemaConfiguration configuration = new SchemaConfiguration(JsonSch
 
 // String validation
 String validatedPayload = Schema.PatternWithoutDelimiter.validate(
-    "a",
+    "AUR,rZ#UM/?R,Fp^l6$ARjbhJk C>",
     configuration
 );
 ```
@@ -356,7 +356,7 @@ static final SchemaConfiguration configuration = new SchemaConfiguration(JsonSch
 
 // String validation
 String validatedPayload = Schema.StringSchema.validate(
-    "a",
+    "A",
     configuration
 );
 ```

src/main/java/org/openapijsonschematools/codegen/generators/DefaultGenerator.java

@@ -20,6 +20,9 @@
 import com.github.benmanes.caffeine.cache.Cache;
 import com.github.benmanes.caffeine.cache.Caffeine;
 import com.github.benmanes.caffeine.cache.Ticker;
+import com.github.curiousoddman.rgxgen.RgxGen;
+import com.github.curiousoddman.rgxgen.config.RgxGenOption;
+import com.github.curiousoddman.rgxgen.config.RgxGenProperties;
 import com.google.common.collect.ImmutableMap;
 import com.samskivert.mustache.Mustache;
 import com.samskivert.mustache.Mustache.Compiler;
@@ -2312,6 +2315,28 @@ private Object getNumberFromSchema(CodegenSchema schema) {
         }
     }
 
+    private String getPatternExample(CodegenPatternInfo patternInfo) {
+        String extractedPattern = patternInfo.pattern;
+        LinkedHashSet<String> regexFlags = patternInfo.flags;
+                /*
+                RxGen does not support our ECMA dialect https://github.com/curious-odd-man/RgxGen/issues/56
+                So strip off the leading / and trailing / and turn on ignore case if we have it
+                 */
+        RgxGen rgxGen;
+        if (regexFlags != null && regexFlags.contains("i")) {
+            rgxGen = new RgxGen(extractedPattern);
+            RgxGenProperties properties = new RgxGenProperties();
+            RgxGenOption.CASE_INSENSITIVE.setInProperties(properties, true);
+            rgxGen.setProperties(properties);
+        } else {
+            rgxGen = new RgxGen(extractedPattern);
+        }
+
+        // this seed makes it so if we have [a-z] we pick a
+        Random random = new Random(18);
+        return rgxGen.generate(random);
+    }
+
     private Object getStringFromSchema(CodegenSchema schema) {
         if (schema.enumInfo != null && schema.enumInfo.typeToValues.containsKey("string")) {
             for(EnumValue enumValue: schema.enumInfo.typeToValues.get("string")) {
@@ -2325,6 +2350,9 @@ private Object getStringFromSchema(CodegenSchema schema) {
             }
         }
         // todo handle not const or not enum here
+        if (schema.patternInfo != null) {
+            return getPatternExample(schema.patternInfo);
+        }
         if ("date".equals(schema.format)) {
             return "2020-12-13";
         } else if ("date-time".equals(schema.format)) {