reuse builder methods when initializing from environment

We can just pass the environment variable to other pre-existing methods
instead of parsing the URL twice. This also fixes URLs without explicit
ports where we should not store "-1" in this case.

src/test/java/de/stklcode/jvault/connector/HTTPVaultConnectorBuilderTest.java

@@ -41,6 +41,8 @@ import static org.junit.jupiter.api.Assertions.*;
  */
 class HTTPVaultConnectorBuilderTest {
     private static final String VAULT_ADDR = "https://localhost:8201";
+    private static final String VAULT_ADDR_2 = "http://localhost";
+    private static final String VAULT_ADDR_3 = "https://localhost/vault/";
     private static final Integer VAULT_MAX_RETRIES = 13;
     private static final String VAULT_TOKEN = "00001111-2222-3333-4444-555566667777";
 
@@ -115,6 +117,22 @@ class HTTPVaultConnectorBuilderTest {
 
             return null;
         });
+        withVaultEnv(VAULT_ADDR_2, null, null, null).execute(() -> {
+            HTTPVaultConnectorBuilder builder = assertDoesNotThrow(
+                    () -> HTTPVaultConnector.builder().fromEnv(),
+                    "Factory creation from minimal environment failed"
+            );
+            assertEquals(VAULT_ADDR_2 + "/v1/", getRequestHelperPrivate(builder.build(), "baseURL"), "URL without port not set correctly");
+            return null;
+        });
+        withVaultEnv(VAULT_ADDR_3, null, null, null).execute(() -> {
+            HTTPVaultConnectorBuilder builder = assertDoesNotThrow(
+                    () -> HTTPVaultConnector.builder().fromEnv(),
+                    "Factory creation from minimal environment failed"
+            );
+            assertEquals(VAULT_ADDR_3, getRequestHelperPrivate(builder.build(), "baseURL"), "URL with custom path not set correctly");
+            return null;
+        });
 
         // Provide address and number of retries.
         withVaultEnv(VAULT_ADDR, null, VAULT_MAX_RETRIES.toString(), null).execute(() -> {