#fixed code
                                public Object getValue(Object ctx, Object elCtx, VariableResolverFactory variableFactory) {
        // return Math.sqrt(DataConversion.convert(p0.getValue(ctx, variableFactory), Double.class).doubleValue());
        for (Method m : Math.class.getMethods()) {
            if ("sqrt".equals(m.getName())) {
                return m;
            }
        }

        return null;
    }
#vulnerable code 
                                public Object getValue(Object ctx, Object elCtx, VariableResolverFactory variableFactory) {
        return Math.sqrt(DataConversion.convert(p0.getValue(ctx, variableFactory), Double.class).doubleValue());
    } 
                            #location 2 
                            #vulnerability type NULL_DEREFERENCE