Redundant if in code block

I have following checks on input json and schema. I use intelliJ and it's static code analysis is saying condition shcema != null is always true.

if (json == null && schema == null){
    return;
}

if ((json == null && schema != null) || (json != null && schema == null)){
    throw new InvalidRequestException("error message");
} else try {
    JsonSchema jsonSchema = JsonSchemaFactory.byDefault().getJsonSchema(schema);
    ProcessingReport processingReport = jsonSchema.validate(json);
    ...
} catch ( ... ) { ... }

Now, if i don't put in the first if condition where i am checking both objects, i might miss a use-case where its okay not to provide anything. Thats why i am using return in first if and not an exception.

What am i missing here