### Question:
ColumnMetaData { public static ColumnMetaData getInstance(String columnName, SqlTypes columnType) { Validate.notBlank(columnName, "columnName must not be null"); Validate.notNull(columnType, "columnType must not be null"); String key = columnName + ":" + columnType.toString(); if (columnMetaDataMap.containsKey(key)) { return columnMetaDataMap.get(key); } ColumnMetaData columnMetaData = new ColumnMetaData(columnName, columnType); columnMetaDataMap.put(key, columnMetaData); return columnMetaData; } private  ColumnMetaData(String columnName, SqlTypes columnType); static ColumnMetaData getInstance(String columnName, SqlTypes columnType); String getName(); int getSize(); boolean isHasSize(); SqlTypes getType(); boolean isHasDefaultValue(); @Override int hashCode(); @Override boolean equals(Object obj); @Override String toString(); String getDefaultValue(); boolean isNullable(); boolean isAutoincrement(); ColumnMetaData setNullable(boolean nullable); ColumnMetaData setSize(int size); ColumnMetaData setDefaultValue(String defaultValue); ColumnMetaData setAutoincrement(boolean autoincrement); ColumnMetaData setComment(String comment); String getComment(); boolean hasComment();  }### Answer:
@Test(expectedExceptions = NullPointerException.class) public void constructThrowsExceptionWhenColumnTypeIsNull() { ColumnMetaData tableColumn = ColumnMetaData.getInstance("columnTypeA", null); }
@Test(expectedExceptions = NullPointerException.class) public void constructThrowsExceptionWhenColumnNaemIsNull() { ColumnMetaData tableColumn = ColumnMetaData.getInstance(null, SqlTypes.INT); }