Panic when read parquet file with field "__index_level_0__"

[icefed]

We get panic when read parquet file, the file is created by pandas.
apache/arrow#2244

panic: reflect.StructOf: field "__index_level_0__" is unexported but missing PkgPath

goroutine 1 [running]:
reflect.runtimeStructField(0xc00001a7e0, 0x11, 0x0, 0x0, 0x1512880, 0x13d28e0, 0x0, 0x0, 0x0, 0x0, ...)
	/usr/local/Cellar/go/1.14.2_1/libexec/src/reflect/type.go:2769 +0x1df
reflect.StructOf(0xc000106000, 0x14, 0x27, 0x0, 0x0)
	/usr/local/Cellar/go/1.14.2_1/libexec/src/reflect/type.go:2385 +0x1e3f
github.com/xitongsys/parquet-go/schema.(*SchemaHandler).GetTypes(0xc000013260, 0xc00001c1c2, 0x6, 0xc00001c1c2)
	.../pkg/mod/github.com/xitongsys/[email protected]/schema/gettype.go:78 +0x7ae

[xitongsys]

hi, @icefed
This issue is due to the field name with underline prefix __index_level_0__.
It doesn't have an upper case prefix which is unexported and the reflection can't assign value.
Fix in latest commits.
I have checked it and it works now

parquet-tools.exe -cmd cat
-file .\a.parquet
[{"One":-1,"Two":"foo","Three":true,"P___index_level_0__":"a"},{"One":null,"Two":"bar","Three":
false,"P___index_level_0__":"b"},{"One":2.5,"Two":"baz","Three":true,"P___index_level_0__":"c"}
]

[icefed]

hi, @icefed
This issue is due to the field name with underline prefix __index_level_0__.
It doesn't have an upper case prefix which is unexported and the reflection can't assign value.
Fix in latest commits.
I have checked it and it works now

parquet-tools.exe -cmd cat
-file .\a.parquet
[{"One":-1,"Two":"foo","Three":true,"P___index_level_0__":"a"},{"One":null,"Two":"bar","Three":
false,"P___index_level_0__":"b"},{"One":2.5,"Two":"baz","Three":true,"P___index_level_0__":"c"}
]

Thank you!