Some of the headful tests are actually headless and works without any GUI and passing on headless machines. If the headful keyword is removed from these tests, we can better manage the scarce headful resources and also the headless coverage would be improved.
This list is prepared by running all the open regression headful tests in a headless OEL aarch64 machine and filtering out all the passing headful tests, ideally these should not pass in a headless machine.
I will analyse each and every test in this list and filter out the genuinely headless ones and will remove the headless keyword from those after proper testing.

The initial list is given below:
1 sun/java2d/xrender/HugeGradientTest.java
2 jdk/editpad/EditPadTest.java
3 javax/swing/UIDefaults/8146330/UIDefaultKeySizeTest.java
4 javax/swing/tree/DefaultTreeCellRenderer/bug4180224.java
5 javax/swing/text/html/Test4783068.java
6 javax/swing/text/html/8218674/TooltipImageTest.java
7 javax/swing/Security/6938813/bug6938813.java
8 javax/swing/RepaintManager/DisplayListenerLeak/DisplayListenerLeak.java
9 javax/swing/plaf/synth/Test6660049.java
10 javax/swing/plaf/nimbus/NimbusPropertiesDoNotImplUIResource.java
11 javax/swing/plaf/gtk/TestCustomStyleFactory.java
12 javax/swing/plaf/basic/BasicHTML/bug4248210.java
13 javax/swing/plaf/basic/BasicComboBoxUI/BasicComboNPE.java
14 javax/swing/LookAndFeel/SystemLookAndFeel/SystemLookAndFeelTest.java
15 javax/swing/LookAndFeel/8145547/DemandGTK3.sh
16 javax/swing/JTree/bug8038113.java
17 javax/swing/JToolTip/TestTooltipBackgroundColor.java
18 javax/swing/JToolTip/FastTooltipSwitchIAE.java
19 javax/swing/JTextPane/TestJTextPaneBackgroundColor.java
20 javax/swing/JTableHeader/SerializeJTableHeader.java
21 javax/swing/JTable/NullTableHeader.java
22 javax/swing/JTable/DefaultRowSorterCacheTest.java
23 javax/swing/JSpinner/TestSelectedTextBackgroundColor.java
24 javax/swing/JSpinner/SerializationTest.java
25 javax/swing/JSpinner/WrongEditorTextFieldFont/FontSetByLaF.java
26 javax/swing/JSlider/TestJSliderRendering.java
27 javax/swing/JSlider/6794836/bug6794836.java
28 javax/swing/JProgressBar/TestProgressBarBorder.java
29 javax/swing/JProgressBar/TestJProgressBarHighlightColor.java
30 javax/swing/JPopupMenu/bug4197019.java
31 javax/swing/JPopupMenu/6583251/bug6583251.java
32 javax/swing/JPasswordField/TestSelectedTextBackgroundColor.java
33 javax/swing/JMenuItem/8216971/DoubleActionTest.java
34 javax/swing/JMenuItem/6883341/bug6883341.java
35 javax/swing/JMenu/JMenuSelectedColorTest.java
36 javax/swing/JList/TestOpaqueListTable.java
37 javax/swing/JList/SetSelectedValueTest.java
38 javax/swing/JList/GetSelectedValueTest.java
39 javax/swing/JList/GetSelectedValuesListTest.java
40 javax/swing/JFormattedTextField/TestSelectedTextBackgroundColor.java
41 javax/swing/JFileChooser/FileChooserListenerLeak.java
42 javax/swing/JFileChooser/8080628/bug8080628.java#id1
43 javax/swing/JFileChooser/8010718/bug8010718.java
44 javax/swing/JFileChooser/6713352/bug6713352.java
45 javax/swing/JFileChooser/4966171/bug4966171.java
46 javax/swing/JFileChooser/4525475/JFileChooserReadOnlyTest.java
47 javax/swing/JDialog/6639507/bug6639507.java
48 javax/swing/JComboBox/DisabledComboBoxFontTestAuto.java
49 javax/swing/JColorChooser/Test4711996.java
50 javax/swing/JColorChooser/Test4461329.java
51 javax/swing/JColorChooser/Test4193384.java
52 javax/swing/JColorChooser/Test4165217.java
53 javax/swing/JCheckBox/ImageCheckboxFocus/ImageCheckboxTest.java
54 javax/sound/sampled/Clip/DataPusherThreadCheck.java
55 javax/accessibility/6714324/TabbedPaneMemLeak.java
56 javax/accessibility/4702199/AccessibleExtendedTextTest.java
57 javax/accessibility/4170173/AccessibleJTextBeforeIndexTest.java
58 javax/accessibility/4170173/AccessibleJTextAfterIndexTest.java
59 java/awt/Window/WindowTitleVisibleTest/WindowTitleVisibleTestLinuxGnome.java
60 java/awt/Window/MultiWindowApp/ChildAlwaysOnTopTest.java
61 java/awt/TrayIcon/TrayIconRemoveTest/TrayIconRemoveTest.java
62 java/awt/TrayIcon/TrayIconSizeTest/TrayIconSizeTest.java
63 java/awt/TrayIcon/PropertyChangeListenerTest.java
64 java/awt/TrayIcon/TrayIconAddTest/TrayIconAddTest.java
65 java/awt/TrayIcon/TrayIconMethodsTest/TrayIconMethodsTest.java
66 java/awt/TrayIcon/SystemTrayInstance/SystemTrayInstanceTest.java#id1
67 java/awt/TrayIcon/PopupMenuLeakTest/PopupMenuLeakTest.java
68 java/awt/TrayIcon/InterJVMTest/InterJVM.java
69 java/awt/TrayIcon/RightClickWhenBalloonDisplayed/RightClickWhenBalloonDisplayed.java
70 java/awt/TrayIcon/GetTrayIconsTest/GetTrayIcons.java
71 java/awt/TrayIcon/ActionEventTest/ActionEventTest.java
72 java/awt/TrayIcon/CtorTest/CtorTest.java
73 java/awt/Toolkit/DesktopProperties/rfe4758438.java
74 java/awt/Toolkit/BadDisplayTest/BadDisplayTest.java
75 java/awt/TextField/DisposeTest/TestDispose.java
76 java/awt/TextArea/DisposeTest/TestDispose.java
77 java/awt/Robot/CreateRobotCustomGC/CreateRobotCustomGC.java
78 java/awt/print/PrinterJob/PrintTextPane.java
79 java/awt/print/PrinterJob/PaintText.java
80 java/awt/MenuBar/MenuNPE/MenuNPE.java
81 java/awt/List/SetBackgroundTest/SetBackgroundTest.java
82 java/awt/KeyboardFocusmanager/PropertySupportNPETest.java
83 java/awt/KeyboardFocusmanager/ChangeKFMTest.java
84 java/awt/im/6396526/IMLookAndFeel.java
85 java/awt/Graphics2D/WhiteTextColorTest.java
86 java/awt/Graphics/IncorrectFractionalClip/IncorrectFractionalClip.java
87 java/awt/FullScreen/UninitializedDisplayModeChangeTest/UninitializedDisplayModeChangeTest.java
88 java/awt/Frame/SetMaximizedBounds/MaximizedMovedWindow.java
89 java/awt/Frame/LayoutOnMaximizeTest/LayoutOnMaximizeTest.java
90 java/awt/Frame/MaximizedByPlatform/MaximizedByPlatform.java
91 java/awt/Frame/ExceptionOnSetExtendedStateTest/ExceptionOnSetExtendedStateTest.java
92 java/awt/FontClass/HelvLtOblTest.java
93 java/awt/FontClass/SurrogateTest/SuppCharTest.java
94 java/awt/font/TextLayout/TestSinhalaChar.java
95 java/awt/font/TextLayout/MyanmarTextTest.java
96 java/awt/Focus/AsyncUpFocusCycleTest.java
97 java/awt/Focus/SortingFPT/JDK8048887.java
98 java/awt/FileDialog/ISCthrownByFileListTest/ISCthrownByFileListTest.java
99 java/awt/FileDialog/8017487/bug8017487.java
100 java/awt/FileDialog/8003399/bug8003399.java
101 java/awt/event/SequencedEvent/MultipleContextsUnitTest.java
102 java/awt/event/KeyEvent/DeadKey/DeadKeyMacOSXInputText.java
103 java/awt/event/KeyEvent/DeadKey/deadKeyMacOSX.java
104 java/awt/event/KeyEvent/8020209/bug8020209.java
105 java/awt/EmbeddedFrame/GraphicsConfigTest/GraphicsConfigTest.java
106 java/awt/Dialog/NonResizableDialogSysMenuResize/NonResizableDialogSysMenuResize.java
107 java/awt/Desktop/EditPrintFolder.java
108 java/awt/Desktop/DesktopSupportTest.java
109 java/awt/datatransfer/MissedHtmlAndRtfBug/MissedHtmlAndRtfBug.java
110 java/awt/datatransfer/FileTransferAWTLockTest/FileTransferAWTLockTest.java
111 java/awt/datatransfer/DragUnicodeBetweenJVMTest/DragUnicodeBetweenJVMTest.java
112 java/awt/datatransfer/DataConversionDeadlockTest/DataConversionDeadlockTest.java
113 java/awt/datatransfer/CRLFTest/CRLFTest.java
114 java/awt/Clipboard/SerializeLocalFlavorTest.java
115 com/sun/java/swing/plaf/gtk/Test6635110.java
116 com/sun/java/swing/plaf/gtk/4928019/bug4928019.java
117 com/sun/java/swing/plaf/gtk/Test6963870.java