HHH-3192 - SchemaValidator nullability check

Author: sebersole

hibernate-core/src/main/java/org/hibernate/tool/schema/internal/AbstractSchemaValidator.java

@@ -139,6 +139,7 @@ protected void validateTable(
 				);
 			}
 			validateColumnType( table, column, existingColumn, metadata, dialect );
+			validateColumnNullability( table, column, existingColumn, metadata, dialect );
 		}
 	}
 
@@ -164,6 +165,21 @@ protected void validateColumnType(
 		}
 	}
 
+	private void validateColumnNullability(Table table, Column column, ColumnInformation existingColumn, Metadata metadata, Dialect dialect) {
+		if ( existingColumn.getNullable() == Boolean.FALSE ) {
+			// the existing schema column is defined as not-nullable
+			if ( column.isNullable() ) {
+				// but it is mapped in the model as nullable
+				throw new SchemaManagementException(
+						String.format(
+								"Schema validation: column defined as not-null in the database, but nullable in model [%s]",
+								column.getName()
+						)
+				);
+			}
+		}
+	}
+
 	protected void validateSequence(Sequence sequence, SequenceInformation sequenceInformation) {
 		if ( sequenceInformation == null ) {
 			throw new SchemaManagementException(