5.6: After disabling the Java Request sampler, it cannot be enabled again

[LeeBaul]

Expected behavior

In version 5.6 of jmeter, I used a java request sampler in my script. When I disable a Java request sampler and enable it again, the GUI page displays successful activation. When I click on other components, it automatically sets it to disabled status.
In jmeter version 5.5, this phenomenon was not replicated.

Actual behavior

I am using org. apache. jmeter. protocol. java. test. JavaTest, and this issue also exists when I switch to my own customized Java sample request.

Steps to reproduce the problem

in Thread Group disable Java Request1

enable again Java Request1 , GUI display enabled successfully.

When I click on other requests, it automatically switches to a disabled state.

JMeter Version

5.6

Java Version

sun jdk version 1.8.0_201

OS Version

Microsoft Windows [版本 10.0.22621.1848]

[vlsi]

The reason is that JavaTestSamplerGui re-creates the sampler instead of configuring the existing element:

jmeter/src/protocol/java/src/main/java/org/apache/jmeter/protocol/java/control/gui/JavaTestSamplerGui.java

Lines 80 to 82 in b47c658

	JavaConfig config = (JavaConfig) javaPanel.createTestElement();
	configureTestElement(sampler);
	sampler.addTestElement(config);

javaPanel.createTestElement creates config element with enabled=false state since AbstractJMeterGuiComponent.enabled was initialized with false.

---

The thing can be fixed in several ways:
a) Skip TestElement.enabled in org.apache.jmeter.testelement.AbstractTestElement#mergeIn. The drawback is there might be other properties with similar pitfalls.
b) Pass "isEnabled" to org.apache.jmeter.protocol.java.control.gui.JavaTestSamplerGui#javaPanel. It would resolve the issue, however, the drawback is that there might be other samplers with similar pitfalls (==creating dummy elements and merging them)
c) something else