Fix PartitionKey.None.toString() throws an exception

[FredGao-new]

#8499

PartitionKey.None.toString() throws an exception:

Java: 11

Jackson: 2.10.1

azure-cosmos 3.6.0

    @Test 
    void testPartitionKeyNoneToString() { 
        com.azure.data.cosmos.PartitionKey.None.toString(); 
    } 

The exception happened in the following code:

azure-sdk-for-java/sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/routing/PartitionKeyInternal.java

Line 246 in 660bc29

for (IPartitionKeyComponent componentValue : partitionKey.getComponents()) {

partitionKey.getComponents() return null in the "for" loop.

Is it ok to add a null check for partitionKey.getComponents before the for loop?

@jongio

[kushagraThapar]

@mbhaskar - Please take a look at this.