Issue #89 Fix int32 type validation to reject decimal values like 3.14

- Added BigDecimal fractional part checking in validateInteger method
- Added test case testInt32RejectsDecimal() to verify the fix
- Ensures all integer types (int8, uint8, int16, uint16, int32, uint32) reject decimal values
- Maintains RFC 8927 compliance for integer type validation

Author: simbo1905

json-java21-jtd/src/main/java/json/java21/jtd/JtdSchema.java

@@ -244,6 +244,11 @@ Jtd.Result validateInteger(JsonValue instance, String type, boolean verboseError
           return Jtd.Result.failure(Jtd.Error.EXPECTED_INTEGER.message());
         }
 
+        // Handle BigDecimal - check if it has fractional part
+        if (value instanceof java.math.BigDecimal bd && bd.scale() > 0) {
+          return Jtd.Result.failure(Jtd.Error.EXPECTED_INTEGER.message());
+        }
+        
         // Convert to long for range checking
         long longValue = value.longValue();
 

json-java21-jtd/src/test/java/json/java21/jtd/TestRfc8927.java

@@ -2,6 +2,7 @@
 
 import jdk.sandbox.java.util.json.Json;
 import jdk.sandbox.java.util.json.JsonValue;
+import jdk.sandbox.java.util.json.JsonNumber;
 import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -440,4 +441,32 @@ public void testRefSchemaRecursiveBad() throws Exception {
       .as("Recursive ref should reject heterogeneous nested data")
       .isFalse();
   }
+
+  /// Micro test to debug int32 validation with decimal values
+  /// Should reject non-integer values like 3.14 for int32 type
+  @Test
+  public void testInt32RejectsDecimal() throws Exception {
+    JsonValue schema = Json.parse("{\"type\": \"int32\"}");
+    JsonValue decimalValue = JsonNumber.of(new java.math.BigDecimal("3.14"));
+    
+    LOG.info(() -> "Testing int32 validation against decimal value 3.14");
+    LOG.fine(() -> "Schema: " + schema);
+    LOG.fine(() -> "Instance: " + decimalValue);
+    
+    Jtd validator = new Jtd();
+    Jtd.Result result = validator.validate(schema, decimalValue);
+    
+    LOG.fine(() -> "Validation result: " + (result.isValid() ? "VALID" : "INVALID"));
+    if (!result.isValid()) {
+      LOG.fine(() -> "ERRORS: " + result.errors());
+    }
+    
+    // This should be invalid - int32 should reject decimal values
+    assertThat(result.isValid())
+      .as("int32 should reject decimal value 3.14")
+      .isFalse();
+    assertThat(result.errors())
+      .as("Should have validation errors for decimal value")
+      .isNotEmpty();
+  }
 }