Fix Bug 1433 decimal literal in C# maybe other languages (#1436)

* Trivial change to kick PR again

* Fix issue 1433 (default decimal literal broken for C#)

* Replace tab with space

* update samples

modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultGenerator.java

@@ -804,7 +804,7 @@ public class DefaultGenerator extends AbstractGenerator implements Generator {
             IOUtils.copy(in, out);
             out.close();
         } else {
-            LOGGER.error("can't open '" + templateFile + "' for input, can not write '" + filename + "'");
+            LOGGER.error("can't open '" + templateFile + "' for input; cannot write '" + filename + "'");
         }
         return outputFile;
     }

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractCSharpCodegen.java

@@ -775,8 +775,8 @@ public abstract class AbstractCSharpCodegen extends DefaultCodegen implements Co
                     return p.getDefault().toString() + "F";
                 } else if (ModelUtils.isDoubleSchema(p)) { // double
                     return p.getDefault().toString() + "D";
-                } else {
-                    return p.getDefault().toString();
+                } else {    // decimal
+                    return p.getDefault().toString() + "M";
                 }
             }
         } else if (ModelUtils.isIntegerSchema(p)) {

modules/openapi-generator/src/main/java/org/openapitools/codegen/utils/ModelUtils.java

@@ -401,9 +401,6 @@ public class ModelUtils {
     }
 
     public static boolean isDoubleSchema(Schema schema) {
-        if (schema instanceof NumberSchema) {
-            return true;
-        }
         if (SchemaTypeUtil.NUMBER_TYPE.equals(schema.getType())
                 && SchemaTypeUtil.DOUBLE_FORMAT.equals(schema.getFormat())) { // format: double
             return true;