code: public Map<String, String> persistencePropertiesOverrides(Map<String, String> overridingProperties) {
          if(overridingProperties == null) {
              throw new IllegalArgumentException("the property 'overridingProperties' is not allowed to be null.");
          }
          Map<String, String> overridingProperttiesCopy = new HashMap<>(overridingProperties);
          
          return mergeFilteredMaps(getSystemJavaxPersistenceOverrides(), overridingProperttiesCopy);
      }
docs: Resolves a Union of System.env and System.getProperties() and overridingProperties where the KeyValue-Pairs of the later have the highest precedence.
  @param overridingProperties
  
  @return Map or null if there are no entries that match the Persistence Filter {@link #PROP_FILTER}