fix: simplify PackageURL::validatePath(String, boolean) (#173)

* Simplify `PackageURL::validatePath(String, boolean)`

In the `PackageURL::validatePath(String, boolean)` method, the
`boolean` parameter value is always `true`, so remove it.

* Rename to `validateSubpath`

Author: dwalluck

src/main/java/com/github/packageurl/PackageURL.java

@@ -98,7 +98,7 @@ public PackageURL(final String type, final String namespace, final String name,
         this.name = validateName(name);
         this.version = validateVersion(version);
         this.qualifiers = parseQualifiers(qualifiers);
-        this.subpath = validatePath(subpath, true);
+        this.subpath = validateSubpath(subpath);
         verifyTypeConstraints(this.type, this.namespace, this.name);
     }
 
@@ -371,11 +371,11 @@ private void validateKey(final String value) throws MalformedPackageURLException
         validateChars(value, PackageURL::isValidCharForKey, "qualifier key");
     }
 
-    private String validatePath(final String value, final boolean isSubpath) throws MalformedPackageURLException {
+    private String validateSubpath(final String value) throws MalformedPackageURLException {
         if (value == null || value.isEmpty()) {
             return null;
         }
-        return validatePath(value.split("/"), isSubpath);
+        return validatePath(value.split("/"), true);
     }
 
     private String validatePath(final String[] segments, final boolean isSubpath) throws MalformedPackageURLException {