#vulnerable code 
                             public DefineFunction encodeDefineFunction(){
		String analyzer = getAnalyzer();
		Boolean binary = getBinary();
		String stripAccents = getStripAccents();
		String tokenPattern = getTokenPattern();

		switch(analyzer){
			case "word":
				break;
			default:
				throw new IllegalArgumentException(analyzer);
		}

		if(stripAccents != null){
			throw new IllegalArgumentException(stripAccents);
		} // End if

		if(tokenPattern != null && !("(?u)\\b\\w\\w+\\b").equals(tokenPattern)){
			throw new IllegalArgumentException(tokenPattern);
		}

		ParameterField documentField = new ParameterField(FieldName.create("document"));

		ParameterField termField = new ParameterField(FieldName.create("term"));

		TextIndex textIndex = new TextIndex(documentField.getName())
			.setTokenize(Boolean.TRUE)
			.setLocalTermWeights(binary ? TextIndex.LocalTermWeights.BINARY : null)
			.setExpression(new FieldRef(termField.getName()));

		DefineFunction defineFunction = new DefineFunction("tf", OpType.CONTINUOUS, null)
			.setDataType(DataType.DOUBLE)
			.addParameterFields(documentField, termField)
			.setExpression(textIndex);

		return defineFunction;
	} 
                            #location 7 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                             public DefineFunction encodeDefineFunction(){
		String analyzer = getAnalyzer();
		Boolean binary = getBinary();
		Object preprocessor = getPreprocessor();
		String stripAccents = getStripAccents();
		Splitter tokenizer = getTokenizer();

		switch(analyzer){
			case "word":
				break;
			default:
				throw new IllegalArgumentException(analyzer);
		}

		if(preprocessor != null){
			throw new IllegalArgumentException();
		} // End if

		if(stripAccents != null){
			throw new IllegalArgumentException(stripAccents);
		}

		ParameterField documentField = new ParameterField(FieldName.create("text"));

		ParameterField termField = new ParameterField(FieldName.create("term"));

		TextIndex textIndex = new TextIndex(documentField.getName())
			.setTokenize(Boolean.TRUE)
			.setWordSeparatorCharacterRE(tokenizer.getSeparatorRE())
			.setLocalTermWeights(binary ? TextIndex.LocalTermWeights.BINARY : null)
			.setExpression(new FieldRef(termField.getName()));

		DefineFunction defineFunction = new DefineFunction("tf", OpType.CONTINUOUS, null)
			.setDataType(DataType.DOUBLE)
			.addParameterFields(documentField, termField)
			.setExpression(textIndex);

		return defineFunction;
	}