**Describe the unexpected behaviour**
maxMap is removing entries with empty string or zero value.

**How to reproduce**

String array
SELECT maxMap(a, b) from values ('a Array(String), b Array(String)',(['A'],['']),(['B'],['']));

┌─maxMap(a, b) ─┐
│ ([],[])                    │ 
└───────────┘

Numeric array
`SELECT maxMap(a, b) from values ('a Array(String), b Array(UInt64)',(['A'],[0]),(['B'],[0]));

┌─maxMap(a, b) ─┐
│ ([],[])                    │ 
└───────────┘
`
It happens with all versions published.

**Expected behavior**
We expect this to maintain those keys with its value (empty string or zero).

#pragma once
#include <IO/WriteHelpers.h>
#include <IO/ReadHelpers.h>
#include <DataTypes/DataTypeArray.h>
#include <DataTypes/DataTypeTuple.h>
#include <DataTypes/DataTypeNullable.h>
#include <Columns/ColumnArray.h>
#include <Columns/ColumnTuple.h>
#include <Columns/ColumnVector.h>
#include <Columns/ColumnDecimal.h>
#include <Columns/ColumnString.h>
#include <Common/FieldVisitors.h>
#include <Common/assert_cast.h>
#include <AggregateFunctions/IAggregateFunction.h>
#include <map>
namespace DB
{
namespace ErrorCodes
{
    extern const int BAD_ARGUMENTS;