Q:

Problem passing parameter from LWC to Apex method

I am having trouble getting the current record Id paramater in a LWC and passing it to an Apex method. Am I missing something? How can this be done?
LWC wire method:
@wire(getOpportunityLineItems, {oppId: this.RecordId})
 contacts(result) {
     this.refreshTable = result;
     if (result.data) {
         this.data = result.data.map(row=>{
             return{...row, productName: row.Product2.Name}
         })
         this.error = undefined;

     } else if (result.error) {
         this.error = result.error;
         this.data = undefined;
     }

 }

Apex Method with SOQL 
 @AuraEnabled(Cacheable = true)
public static List<OpportunityLineItem> getOpportunityLineItem(Id oppId){

    return [SELECT Id, Product2Id, Product2.Name, Name, Quantity, UnitPrice, ProductCode FROM OpportunityLineItem WHERE OpportunityId= :oppId];

}

A:

If you're using the standard record Id API, it should be recordId, not RecordId (case-sensitive), and you should be using a reactive parameter:
@api recordId;
@wire(getOpportunityLineItems, {oppId: '$recordId'})

